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Holocene New Zealand sea lion (Phocarctos hookeri) bones collected from the north of New Zealand's South Island strengthen existing evidence for the former Holocene presence of breeding colonies ofP. hookerion mainland New Zealand. The taxonomic identity ofPhocarctosbones is confirmed using both morphology and ancient DNA analysis. Five radiocarbon dates on four adult and one pup bone from Creighton's Cave near Paturau, northwest Nelson, ranged from 1290±30 yr BP to 5430±30 yr BP. Three radiocarbon dates on pup bones spanning 20014C yr (1550±30 yr BP to 1390±30 yr BP) reveal that a prehistoric breeding rookery was present at Delaware Bay, Nelson, until shortly before the time of human arrival c. AD 1280 (670 yr BP). The Delaware Bay site in particular provides a valuable ‘snapshot’ of coastal New Zealand faunas shortly before human arrival, one that has potential to enhance our understanding of changes in the endemic coastal fauna associated with human colonisation. [ABSTRACT FROM AUTHOR]

Long-term memory undergoes pronounced development in the latter part of the 1st year. This research combines electrophysiological (event-related potential [ERP]) and behavioral (deferred imitation) measures of encoding and recall, respectively, in an examination of age-related changes in and relations between encoding and recall during this time. In a short-term longitudinal study, infants were exposed to different multistep sequences at 9 and at 10 months. In both phases, they were tested for immediate recognition of the events via ERPs (as an index of encoding), and for recall of them 1 month later. At both ages, infants encoded the events; encoding was more robust at 10 months than at 9 months. After the 1-month delay, infants failed to recall the events experienced at 9 months, but evidenced recall of the events experienced at 10 months. In spite of developmental differences in encoding and recall over this period, indexes of encoding at 9 months were correlated with measures of recall of events experienced at 10 months and tested 1 month later. [ABSTRACT FROM AUTHOR]

Rapid adaptation is thought to be critical for the survival of species under global change, but our understanding of human-induced evolution in the wild remains limited. We show that widespread deforestation has underpinned repeated color shifts in wild insect populations. Specifically, loss of forest has led to color changes across lineages that mimic the warning coloration of a toxic forest stonefly. Predation experiments suggest that the relative fitness of color phenotypes varies between forested and deforested habitats. Genomic and coloration analyses of 1200 specimens show repeated selection at the ebony locus controlling color polymorphism across lineages. These findings represent an example of human-driven evolution linked to altered species interactions, highlighting the possibility for populations to adapt rapidly in the wake of sudden environmental change.

Identification of taxonomically cryptic species is essential for the effective conservation of biodiversity. Freshwater-limited organisms tend to be genetically isolated by drainage boundaries, and thus may be expected to show substantial cryptic phylogenetic and taxonomic diversity. By comparison, populations of diadromous taxa, that migrate between freshwater and marine environments, are expected to show less genetic differentiation. Here we test for cryptic diversity in Australasian populations (both diadromous and non-diadromous) of two widespread Southern Hemisphere fish species, Galaxias brevipinnis and Galaxias maculatus . Both mtDNA and nuclear markers reveal putative cryptic species within these taxa. The substantial diversity detected within G. brevipinnis may be explained by its strong climbing ability which allows it to form isolated inland populations. In island populations, G. brevipinnis similarly show deeper genetic divergence than those of G. maculatus , which may be explained by the greater abundance of G. maculatus larvae in the sea allowing more ongoing dispersal. Our study highlights that even widespread, 'high-dispersal' species can harbour substantial cryptic diversity and therefore warrant increased taxonomic and conservation attention., Competing Interests: The authors declare that they have no conflict of interest., (© 2024 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

Understanding the landscape factors governing population connectivity in riverine ecosystems represents an ongoing challenge for freshwater biologists. We used DNA sequence analysis to test the hypothesis that major geomorphological features underpin freshwater-limited fish diversity in a tectonically dynamic region of New Zealand. Phylogeographic analysis of 101 Galaxias depressiceps cytochrome b sequences, incorporating 55 localities from southern New Zealand, revealed 26 haplotypes, with only one shared among rivers. We detect strong hierarchical genetic differentiation both among and within river systems. Genetic structuring is particularly pronounced across the Taieri River system (63 individuals from 35 sites, 18 haplotypes), with 92% of variation partitioned among locations. Distinctive within-river genetic clusters are invariably associated with major subcatchment units, typically isolated by substantial gorges. The anomalous distribution of a single lineage across a major drainage divide is consistent with local, tectonically driven headwater capture. We conclude that major landscape features such as gorges can strongly partition riverine fish diversity and constrain freshwater biodiversity., (© 2023 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of Fisheries Society of the British Isles.)

Many avian species endemic to Aotearoa New Zealand were driven to extinction or reduced to relict populations following successive waves of human arrival, due to hunting, habitat destruction and the introduction of mammalian predators. Among the affected species were the large flightless South Island takahē (Porphyrio hochstetteri) and the moho (North Island takahē; P. mantelli), with the latter rendered extinct and the former reduced to a single relictual population. Little is known about the evolutionary history of these species prior to their decline and/or extinction. Here we sequenced mitochondrial genomes from takahē and moho subfossils (12 takahē and 4 moho) and retrieved comparable sequence data from takahē museum skins (n = 5) and contemporary individuals (n = 17) to examine the phylogeny and recent evolutionary history of these species. Our analyses suggest that prehistoric takahē populations lacked deep phylogeographic structure, in contrast to moho, which exhibited significant spatial genetic structure, albeit based on limited sample sizes (n = 4). Temporal genetic comparisons show that takahē have lost much of their mitochondrial genetic diversity, likely due to a sudden demographic decline soon after human arrival (~750 years ago). Time-calibrated phylogenetic analyses strongly support a sister species relationship between takahē and moho, suggesting these flightless taxa diverged around 1.5 million years ago, following a single colonisation of New Zealand by a flighted Porphyrio ancestor approximately 4 million years ago. This study highlights the utility of palaeogenetic approaches for informing the conservation and systematic understanding of endangered species whose ranges have been severely restricted by anthropogenic impacts., (© 2023 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.)

Deforestation is considered a major threat to biodiversity across many parts of the globe, but the biological impacts of this dramatic ecosystem disturbance often remain incompletely understood. In New Zealand - the world's last major landmass to be colonised by humans - widespread deforestation over recent centuries has left a highly fragmented suite of relict forest stands, ideal for assessing anthropogenic biological change. We hypothesise that this widespread environmental disturbance has underpinned repeated and predictable ecological shifts across distinct rivers and regions. Here we use freshwater environmental DNA (eDNA) data (113 samples across 38 locations; 89 insect taxa) to test for concordant biological shifts linked to this deforestation. eDNA analyses highlight consistent compositional and functional differentiation between forested versus deforested assemblages, including turnover of 'cryptic' congeneric taxa that are morphologically similar yet ecologically and genetically distinct. These dramatic biological shifts are evident even over fine spatial scales within streams, emphasising the widespread emergence of a novel 'deforested' assemblage. Our results illustrate that environmental change can drive predictable biological shifts across broad geographic regions, and highlight the power of eDNA for assessing anthropogenic ecosystem change over large geographic scales., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jonathan M Waters reports financial support was provided by Royal Society of New Zealand Marsden Fund. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Freshwater ecosystems frequently house diverse assemblages of closely related fish taxa, which can be particularly prone to hybridization and introgression. While extensive introgression may be expected among biogeographically proximate lineages, recent analyses imply that contemporary distributions do not always accurately predict hybridization history. Here, we use the ABBA-BABA approach to test biogeographic hypotheses regarding the extent of hybridization in the recent evolution of New Zealand's species-rich freshwater Galaxias vulgaris fish complex. Genome-wide comparisons reveal significant increases in introgression associated with increasing geographic overlap of taxa. The estimator DP, which assesses the net proportion of a genome originating from introgression, shows a particularly strong relationship with biogeographic overlap (R2 = .43; p = .005). Our analyses nevertheless reveal surprisingly substantial signatures of introgression among taxa that currently have disjunct distributions within drainages (e.g., separate subcatchments). These "anomalies" imply that current biogeography is not always an accurate predictor of introgression history. Our study suggests that both modern and ancient biogeographic shifts, including recent anthropogenic range fragmentation and tectonically driven riven capture events, have influenced introgression histories in this dynamic freshwater fish radiation., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Society for the Study of Evolution (SSE). All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The evolution of Batesian mimicry - whereby harmless species avoid predation through their resemblance to harmful species - has long intrigued biologists. In rare cases, Batesian mimicry is linked to intraspecific colour variation, in which only some individuals within a population resemble a noxious 'model'. Here, we assess intraspecific colour variation within a widespread New Zealand stonefly, wherein highly melanized individuals of Zelandoperla closely resemble a chemically defended aposematic stonefly, Austroperla cyrene. We assess convergence in the colour pattern of these two species, compare their relative palatability to predators, and use genome-wide association mapping to assess the genetic basis of this resemblance. Our analysis reveals that melanized Zelandoperla overlap significantly with Austroperla in colour space but are significantly more palatable to predators, implying that they are indeed Batesian mimics. Analysis of 194,773 genome-wide SNPs reveals an outlier locus (ebony) strongly differentiating melanic versus non-melanic Zelandoperla. Genotyping of 338 specimens from a single Zelandoperla population indicates that ebony explains nearly 70% of the observed variance in melanism. As ebony has a well-documented role in insect melanin biosynthesis, our findings indicate this locus has a conserved function across deeply divergent hexapod lineages. Distributional records suggest a link between the occurrence of melanic Zelandoperla and the forested ecosystems where the model Austroperla is abundant, suggesting the potential for adaptive shifts in this system underpinned by environmental change., (© 2023 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.)

Detached buoyant kelp can disperse thousands of kilometres at sea and can colonize newly available shores in the wake of disturbances that wipe out competitors. Localized earthquake uplift can cause extirpation of intertidal kelp populations followed by recolonization. Sources of recolonizing kelp can be detectable in genomic structure of contemporary populations. Our field observations combined with LiDAR mapping identified a previously unrecognized zone of uplifted rocky coastline in a region that is slowly subsiding. Intertidal kelp ( Durvillaea antarctica ) on the uplifted section of coast is genetically distinctive from nearby populations, with genomic signatures most similar to that of kelp 300 km to the south. Genetic divergence between these locations suggests reproductive isolation for thousands of years. Combined geological and genetic data suggest that this uplift event occurred during one of four major earthquakes between 6000 and 2000 years ago, with one of the younger events most likely. Extirpation of the pre-existing kelp required sudden uplift of approximately 2 metres, precluding several small incremental uplift events. Our results show the power of integrating biological (genomic) analyses with geological data to understand ancient geological processes and their ecological impacts.

Many researchers have questioned the ability of biota to adapt to rapid anthropogenic environmental shifts. Here, we synthesize emerging genomic evidence for rapid insect evolution in response to human pressure. These new data reveal diverse genomic mechanisms (single locus, polygenic, structural shifts; introgression) underpinning rapid adaptive responses to a variety of anthropogenic selective pressures. While the effects of some human impacts (e.g. pollution; pesticides) have been previously documented, here we highlight startling new evidence for rapid evolutionary responses to additional anthropogenic processes such as deforestation. These recent findings indicate that diverse insect assemblages can indeed respond dynamically to major anthropogenic evolutionary challenges. Our synthesis also emphasizes the critical roles of genomic architecture, standing variation and gene flow in maintaining future adaptive potential. Broadly, it is clear that genomic approaches are essential for predicting, monitoring and responding to ongoing anthropogenic biodiversity shifts in a fast-changing world., (© 2022 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)

Large-scale disturbance events have the potential to drastically reshape biodiversity patterns. Notably, newly vacant habitat space cleared by disturbance can be colonized by multiple lineages, which can lead to the evolution of distinct spatial "sectors" of genetic diversity within a species. We test for disturbance-driven sectoring of genetic diversity in intertidal southern bull kelp, Durvillaea antarctica (Chamisso) Hariot, following the high-magnitude 1855 Wairarapa earthquake in New Zealand. Specifically, we use genotyping-by-sequencing (GBS) to analyse fine-scale population structure across the uplift zone and apply machine learning to assess the fit of alternative recolonizaton models. Our analysis reveals that specimens from the uplift zone carry distinctive genomic signatures potentially linked to post-earthquake recolonization processes. Specifically, our analysis identifies two parapatric spatial-genomic sectors of D. antarctica at Turakirae Head, which experienced the most dramatic uplift. Based on phylogeographical modelling, we infer that bull kelp in the Wellington region was probably a source for recolonization of the heavily uplifted Turakirae Head coastline, via two parallel, eastward recolonization events. By identifying multiple parapatric genotypic sectors within a recently recolonized coastal region, the current study provides support for the hypothesis that competing lineage expansions can generate striking spatial structuring of genetic diversity, even in highly dispersive taxa., (© 2022 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.)

Background: Insects have exceptionally fast smelling capabilities, and some can track the temporal structure of odour plumes at rates above 100 Hz. It has been hypothesized that this fast smelling capability is an adaptation for flying. We test this hypothesis by comparing the olfactory acuity of sympatric flighted versus flightless lineages within a wing-polymorphic stonefly species., Results: Our analyses of olfactory receptor neuron responses reveal that recently-evolved flightless lineages have reduced olfactory acuity. By comparing flighted versus flightless ecotypes with similar genetic backgrounds, we eliminate other confounding factors that might have affected the evolution of their olfactory reception mechanisms. Our detection of different patterns of reduced olfactory response strength and speed in independently wing-reduced lineages suggests parallel evolution of reduced olfactory acuity., Conclusions: These reductions in olfactory acuity echo the rapid reduction of wings themselves, and represent an olfactory parallel to the convergent phenotypic shifts seen under selective gradients in other sensory systems (e.g. parallel loss of vision in cave fauna). Our study provides evidence for the hypothesis that flight poses a selective pressure on the speed and strength of olfactory receptor neuron responses and emphasizes the energetic costs of rapid olfaction., (© 2022. The Author(s).)

Major ecological disturbance events can provide opportunities to assess multispecies responses to upheaval. In particular, catastrophic disturbances that regionally extirpate habitat-forming species can potentially influence the genetic diversity of large numbers of codistributed taxa. However, due to the rarity of such disturbance events over ecological timeframes, the genetic dynamics of multispecies recolonization processes have remained little understood. Here, we use single nucleotide polymorphism (SNP) data from multiple coastal species to track the dynamics of cocolonization events in response to ancient earthquake disturbance in southern New Zealand. Specifically, we use a comparative phylogeographic approach to understand the extent to which epifauna (with varying ecological associations with their macroalgal hosts) share comparable spatial and temporal recolonization patterns. Our study reveals concordant disturbance-related phylogeographic breaks in two intertidal macroalgal species along with two associated epibiotic species (a chiton and an isopod). By contrast, two codistributed species, one of which is an epibiotic amphipod and the other a subtidal macroalga, show few, if any, genetic effects of palaeoseismic coastal uplift. Phylogeographic model selection reveals similar post-uplift recolonization routes for the epibiotic chiton and isopod and their macroalgal hosts. Additionally, codemographic analyses support synchronous population expansions of these four phylogeographically similar taxa. Our findings indicate that coastal paleoseismic activity has driven concordant impacts on multiple codistributed species, with concerted recolonization events probably facilitated by macroalgal rafting. These results highlight that high-resolution comparative genomic data can help reconstruct concerted multispecies responses to recent ecological disturbance., (© 2021 John Wiley & Sons Ltd.)

Jonathan Waters provides an introduction to seaweed rafts and their role in the dispersal of marine and coastal species., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Natural selection along elevational gradients has potential to drive predictable adaptations across distinct lineages, but the extent of such repeated evolution remains poorly studied for many widespread alpine taxa. We present parallel genomic analyses of two recently evolved flightless alpine insect lineages to test for molecular signatures of repeated alpine adaptation. Specifically, we compare low-elevation vs. alpine stonefly ecotypes from parallel stream populations in which flightless upland ecotypes have been independently derived. We map 67,922 polymorphic genetic markers, generated across 176 Zelandoperla fenestrata specimens from two independent alpine stream populations in New Zealand's Rock and Pillar Range, to a newly developed plecopteran reference genome. Genome-wide scans revealed 31 regions with outlier single nucleotide polymorphisms (SNPs) differentiating lowland vs. alpine ecotypes in Lug Creek, and 37 regions with outliers differentiating ecotypes in Six Mile Creek. Of these regions, 13% (8/60) yielded outlier SNPs across both within-stream ecotype comparisons, implying comparable genomic shifts contribute to this repeated alpine adaptation. Candidate genes closely linked to repeated outlier regions include several with documented roles in insect wing-development (e.g., dishevelled), suggesting that they may contribute to repeated alpine wing reduction. Additional candidate genes have been shown to influence insect fecundity (e.g., ovo) and lifespan (e.g., Mrp4), implying that they might contribute to life history differentiation between upland and lowland ecotypes. Additional outlier genes have potential roles in the evolution of reproductive isolation among ecotypes (hedgehog and Desaturase 1). These results demonstrate how replicated outlier tests across independent lineages can potentially contribute to the discovery of genes underpinning repeated adaptation., (© 2021 John Wiley & Sons Ltd.)

Understanding the forces that shape species distributions is increasingly important in a fast-changing world. Although major disturbance events can adversely affect natural populations, they can also present new opportunities, for example by opening up habitat for colonization by other lineages. Following extensive geographic sampling, we use genomic data to infer a range extension following disturbance for an ecologically important intertidal macroalgal species. Specifically, we genotyped 288 southern bull kelp (Durvillaea) plants from 28 localities across central New Zealand. All specimens from the North Island were expected to be D. antarctica, but unexpectedly 10 samples from four sites were identified as D. poha. Extensive sampling from the northern South Island (105 samples at five locations) confirmed the absence of D. poha north of the Kaikōura Peninsula. The North Island specimens of D. poha therefore reveal a biogeographic disjunction, some 150 km northeast of the nearest (South Island) population of this species. Based on strong geographic correspondence between these North Island samples and historic disturbance, we infer that tectonic upheaval, particularly earthquake-generated landslides, likely extirpated local D. antarctica and created an opportunity for a northward range expansion event by D. poha. Close phylogenomic relationships between this new North Island population and South Island samples support a geologically recent northward expansion, rather than a deeper evolutionary origin. These findings indicate the potential of large-scale disturbances to facilitate sudden biogeographic range expansions, and they emphasize the ability of genomic analyses with fine-scale sampling to reveal long-lasting signatures of past disturbance, dispersal, and colonization., (© 2021 Phycological Society of America.)

Biologists have long been intrigued by apparently predictable and repetitive evolutionary trajectories inferred across a variety of lineages and systems. In recent years, high-throughput sequencing analyses have started to transform our understanding of such repetitive shifts. While researchers have traditionally categorized such shifts as either "convergent" or "parallel," based on relatedness of the lineages involved, emerging genomic insights provide an opportunity to better describe the actual evolutionary mechanisms at play. A synthesis of recent genomic analyses confirms that convergence is the predominant driver of repetitive evolution among species, whereas repeated sorting of standing variation is the major driver of repeated shifts within species. However, emerging data reveal numerous notable exceptions to these expectations, with recent examples of de novo mutations underpinning convergent shifts among even very closely related lineages, while repetitive sorting processes have occurred among even deeply divergent taxa, sometimes via introgression. A number of very recent analyses have found evidence for both processes occurring on different scales within taxa. We suggest that the relative importance of convergent versus sorting processes depends on the interplay between gene flow among populations, and phylogenetic relatedness of the lineages involved., (© 2021 John Wiley & Sons Ltd.)

Recent genomic analyses have highlighted parallel divergence in response to ecological gradients, but the extent to which altitude can underpin such repeated speciation remains unclear. Wing reduction and flight loss have apparently evolved repeatedly in montane insect assemblages and have been suggested as important drivers of hexapod diversification. We test this hypothesis using genomic analyses of a widespread wing-polymorphic stonefly species complex in New Zealand. We identified over 50,000 polymorphic genetic markers generated across almost 200 Zelandoperla fenestrata stonefly specimens using a newly generated plecopteran reference genome, to reveal widespread parallel speciation between sympatric full-winged and wing-reduced ecotypes. Rather than the existence of a single, widespread, flightless taxon (Zelandoperla pennulata), evolutionary genomic data reveal that wing-reduced upland lineages have speciated repeatedly and independently from full-winged Z. fenestrata. This repeated evolution of reproductive isolation between local ecotype pairs that lack mitochondrial DNA differentiation suggests that ecological speciation has evolved recently. A cluster of outlier single-nucleotide polymorphisms detected in independently wing-reduced lineages, tightly linked in an approximately 85 kb genomic region that includes the developmental "supergene" doublesex, suggests that this "island of divergence" may play a key role in rapid ecological speciation. [Ecological speciation; genome assembly; genomic island of differentiation; genotyping-by-sequencing; incipient species; plecoptera; wing reduction.]., (© The Author(s) 2020. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Anthropogenic environmental change can underpin major shifts in natural selective regimes, and can thus alter the evolutionary trajectories of wild populations. However, little is known about the evolutionary impacts of deforestation-one of the most pervasive human-driven changes to terrestrial ecosystems globally. Absence of forest cover (i.e. exposure) has been suggested to play a role in selecting for insect flightlessness in montane ecosystems. Here, we capitalize on human-driven variation in alpine treeline elevation in New Zealand to test whether anthropogenic deforestation has caused shifts in the distributions of flight-capable and flightless phenotypes in a wing-polymorphic lineage of stoneflies from the Zelandoperla fenestrata species complex. Transect sampling revealed sharp transitions from flight-capable to flightless populations with increasing elevation. However, these phenotypic transitions were consistently delineated by the elevation of local treelines, rather than by absolute elevation, providing a novel example of human-driven evolution in response to recent deforestation. The inferred rapid shifts to flightlessness in newly deforested regions have implications for the evolution and conservation of invertebrate biodiversity.

Although theory predicts that dispersal has a pivotal influence on speciation and extinction rates, it can have contradictory effects on each, such that empirical quantification of its role is required. In many studies, dispersal reduction appears to promote diversification, although some comparisons of migratory and nonmigratory species suggest otherwise. We tested for a relationship between migratory status and diversification rate within the dominant radiation of temperate Southern Hemisphere freshwater fishes, the Galaxiidae. We reconstructed a molecular phylogeny comprising >95% of extant taxa, and applied State-dependent Speciation Extinction models to estimate speciation, extinction, and diversification rates. In contrast to some previous studies, we revealed higher diversification rates in nonmigratory lineages. The reduced gene flow experienced by nonmigratory galaxiids appears to have increased diversification under conditions of allopatry or local adaptation. Migratory galaxiid lineages, by contrast, are genetically homogeneous within landmasses, but may also be rarely able to diversify by colonizing other landmasses in the temperate Southern Hemisphere. Apparent contradictions among studies of dispersal-diversification relationships may be explained by the spatial context of study systems relative to species dispersal abilities, by means of the "intermediate dispersal" model; the accurate quantification of dispersal abilities will aid in the understanding of these proposed interactions., (© 2020 The Authors. Evolution © 2020 The Society for the Study of Evolution.)

Theory suggests that catastrophic earth-history events can drive rapid biological evolution, but empirical evidence for such processes is scarce. Destructive geological events such as earthquakes can represent large-scale natural experiments for inferring such evolutionary processes. We capitalized on a major prehistoric (800 yr BP) geological uplift event affecting a southern New Zealand coastline to test for the lasting genomic impacts of disturbance. Genome-wide analyses of three co-distributed keystone kelp taxa revealed that post-earthquake recolonization drove the evolution of novel, large-scale intertidal spatial genetic 'sectors' which are tightly linked to geological fault boundaries. Demographic simulations confirmed that, following widespread extirpation, parallel expansions into newly vacant habitats rapidly restructured genome-wide diversity. Interspecific differences in recolonization mode and tempo reflect differing ecological constraints relating to habitat choice and dispersal capacity among taxa. This study highlights the rapid and enduring evolutionary effects of catastrophic ecosystem disturbance and reveals the key role of range expansion in reshaping spatial genetic patterns.

Recent biological analyses suggest that reductions in dispersal ability have been key drivers of diversification across numerous lineages. We synthesise emerging data to highlight similarities regarding the causes and consequences of dispersal reduction across taxa and ecosystems, as well as the diverse genomic mechanisms underpinning these shifts. Natural selection has acted on standing genetic variation within taxa to drive often rapid - and in some cases parallel - losses of dispersal, and ultimately speciation. Such shifts can thus represent an important nexus between adaptive and neutral diversification processes, with substantial evolutionary consequences. Recognition of the links between these concepts that are emerging from different fields, taxa and ecosystems is transforming our understanding of the fascinating role of dispersal reduction in the formation of biodiversity., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In species that form dense populations, major disturbance events are expected to increase the chance of establishment for immigrant lineages. Real-time tests of the impact of disturbance on patterns of genetic structure are, however, scarce. Central to testing these concepts is determining the pool of potential immigrants dispersing into a disturbed area. In 2016, a 7.8 magnitude earthquake occurred on the South Island of New Zealand. Affecting approximately 100 km of coastline, this quake caused extensive uplift (several metres high), extirpating many intertidal populations, including keystone intertidal kelp species. Following the uplift, we set out to determine the geographic origins of detached kelp specimens which rafted into the disturbed zone. Specifically, we used genotyping-by-sequencing (GBS) approaches to compare beach-cast southern bull-kelp (Durvillaea antarctica and Durvillaea poha) samples to established populations throughout the species' ranges, and thus infer the geographic origins of potential colonists reaching the disturbed coast. Our findings revealed an ongoing supply of diverse lineages dispersing to the newly uplifted coastline, suggesting potential for establishment of "exotic" lineages following disturbance. Furthermore, we found that some drifting individuals of each species came from far-distant regions, some >1,200 km away. These results show that diverse lineages - in many cases from very distant sources - can compete for new space in the wake of an exceptional disturbance event, illustrating the potential of long-distance dispersal as a key mechanism for reassembly of coastal ecosystems. Furthermore, our findings demonstrate that high-resolution genomic baselines can be used to robustly assign the provenance of dispersing individuals., (© 2019 John Wiley & Sons Ltd.)

Climate shifts are key drivers of ecosystem change. Despite the critical importance of Antarctica and the Southern Ocean for global climate, the extent of climate-driven ecological change in this region remains controversial. In particular, the biological effects of changing sea ice conditions are poorly understood. We hypothesize that rapid postglacial reductions in sea ice drove biological shifts across multiple widespread Southern Ocean species. We test for demographic shifts driven by climate events over recent millennia by analyzing population genomic datasets spanning 3 penguin genera ( Eudyptes , Pygoscelis , and Aptenodytes ). Demographic analyses for multiple species (macaroni/royal, eastern rockhopper, Adélie, gentoo, king, and emperor) currently inhabiting southern coastlines affected by heavy sea ice conditions during the Last Glacial Maximum (LGM) yielded genetic signatures of near-simultaneous population expansions associated with postglacial warming. Populations of the ice-adapted emperor penguin are inferred to have expanded slightly earlier than those of species requiring ice-free terrain. These concerted high-latitude expansion events contrast with relatively stable or declining demographic histories inferred for 4 penguin species (northern rockhopper, western rockhopper, Fiordland crested, and Snares crested) that apparently persisted throughout the LGM in ice-free habitats. Limited genetic structure detected in all ice-affected species across the vast Southern Ocean may reflect both rapid postglacial colonization of subantarctic and Antarctic shores, in addition to recent genetic exchange among populations. Together, these analyses highlight dramatic, ecosystem-wide responses to past Southern Ocean climate change and suggest potential for further shifts as warming continues.

Island formation is a key driver of biological evolution, and several studies have used geological ages of islands to calibrate rates of DNA change. However, many islands are home to "relict" lineages whose divergence apparently pre-dates island age. The geologically dynamic New Zealand (NZ) archipelago sits upon the ancient, largely submerged continent Zealandia, and the origin and age of its distinctive biota have long been contentious. While some researchers have interpreted NZ's biota as equivalent to that of a post-Oligocene island, a recent review of genetic studies identified a sizeable proportion of pre-Oligocene "relict" lineages, concluding that much of the biota survived an incomplete drowning event. Here, we assemble comparable genetic divergence data sets for two recently formed South Pacific archipelagos (Lord Howe; Chatham Islands) and demonstrate similarly substantial proportions of relict lineages. Similar to the NZ biota, our island reviews provide surprisingly little evidence for major genetic divergence "pulses" associated with island emergence. The dominance of Quaternary divergence estimates in all three biotas may highlight the importance of rapid biological turnover and new arrivals in response to recent climatic and/or geological disturbance and change. We provide a schematic model to help account for discrepancies between expected versus observed divergence-date distributions for island biotas, incorporating the effects of both molecular dating error and lineage extinction. We conclude that oceanic islands can represent both evolutionary "cradles" and "museums" and that the presence of apparently archaic island lineages does not preclude dispersal origins., (© 2019 John Wiley & Sons Ltd.)

The study of systematics in wide-ranging seabirds can be challenging due to the vast geographic scales involved, as well as the possible discordance between molecular, morphological and behavioral data. In the Southern Ocean, macaroni penguins (Eudyptes chrysolophus) are distributed over a circumpolar range including populations in Antarctic and sub-Antarctic areas. Macquarie Island, in its relative isolation, is home to a closely related endemic taxon - the royal penguin (Eudyptes schlegeli), which is distinguishable from E. chrysolophus mainly by facial coloration. Although these sister taxa are widely accepted as representing distinct species based on morphological grounds, the extent of their genome-wide differentiation remains uncertain. In this study, we use genome-wide Single Nucleotide Polymorphisms to test genetic differentiation between these geographically isolated taxa and evaluate the main drivers of population structure among breeding colonies of macaroni/royal penguins. Genetic similarity observed between macaroni and royal penguins suggests they constitute a single evolutionary unit. Nevertheless, royal penguins exhibited a tendency to cluster only with macaroni individuals from Kerguelen Island, suggesting that dispersal occurs mainly between these neighboring colonies. A stepping stone model of differentiation of macaroni/royal populations was further supported by a strong pattern of isolation by distance detected across its whole distribution range, possibly driven by large geographic distances between colonies as well as natal philopatry. However, we also detected intraspecific genomic differentiation between Antarctic and sub-Antarctic populations of macaroni penguins, highlighting the role of environmental factors together with geographic distance in the processes of genetic differentiation between Antarctic and sub-Antarctic waters., (Copyright © 2019 Elsevier Inc. All rights reserved.)