Search

Sexual selection has long been thought to increase species diversification. Sexually selected traits, such as sexual signals that contribute to reproductive isolation, were thought to promote diversification. However, studies exploring links between sexually selected traits and species diversification have thus far primarily focused on visual or acoustic signals. Many animals often employ chemical signals (i.e., pheromones) for sexual communications, but large-scale analyses on the role of chemical communications in driving species diversification have been missing. Here, for the first time, we investigate whether traits associated with chemical communications—the presence of follicular epidermal glands—promote diversification across 6,672 lizard species. In most analyses, we found no strong association between the presence of follicular epidermal glands and species diversification rates, either across all lizard species or at lower phylogenetic scales. Previous studies suggest that follicular gland secretions act as species recognition signals that prevent hybridization during speciation in lizards. However, we show that geographic range overlap was no different in sibling species pairs with and without follicular epidermal glands. Together, these results imply that either follicular epidermal glands do not primarily function in sexual communications or sexually selected traits in general (here chemical communication) have a limited effect on species diversification. In our additional analysis accounting for sex-specific differences in glands, we again found no detectable effect of follicular epidermal glands on species diversification rates. Thus, our study challenges the general role of sexually selected traits in broad-scale species diversification patterns. [ABSTRACT FROM AUTHOR]

New Guinea has been considered both as a refuge for mesic rainforest-associated lineages that contracted in response to the late Cenozoic aridification of Australia and as a centre of biotic diversification and radiation since the mid-Miocene or earlier. Here, we estimate the diversity and a phylogeny for the Australo-Papuan forest dragons (Sauria: Agamidae; ~20 species) in order to examine the following: (1) whether New Guinea and/or proto-Papuan Islands may have been a biogeographical refuge or a source for diversity in Australia; (2) whether mesic rainforest environments are ancestral to the entire radiation, as may be predicted by the New Guinea refuge hypothesis; and (3) more broadly, how agamid ecological diversity varies across the contrasting environments of Australia and New Guinea. Patterns of lineage distribution and diversity suggest that extinction in Australia, and colonization and radiation on proto-Papuan islands, have both shaped the extant diversity and distribution of forest dragons since the mid-Miocene. The ancestral biome for all Australo-Papuan agamids is ambiguous. Both rainforest and arid-adapted radiations probably started in the early Miocene. However, despite deep-lineage diversity in New Guinea rainforest habitats, overall species and ecological diversity is low when compared with more arid areas, with terrestrial taxa being strikingly absent. [ABSTRACT FROM AUTHOR]

Mammals and birds provide food for their young after birth, but such provisioning is almost absent in other vertebrates. A recent theory suggested that, in addition to thermoregulation, the large discrepancy in size between adult and young ectothermic vertebrates precludes them from providing for their young, whereas the relatively large offspring of endotherms are easier to provision. I show here that reptile neonates and hatchlings are as large as those of mammals and birds. Differences in size between adults and young thus cannot explain the lack of parental provisioning in reptiles. I suggest that the large size at birth is the ancestral condition in amniotes as a whole and that provisioning has thus evolved after endothermy. [ABSTRACT FROM AUTHOR]

The morphology of organisms reflects a balance between their evolutionary history, functional demands, and biomechanical constraints imposed by the immediate environment. In many fish species, a marked shift in the selection regime is evident when pelagic larvae, which swim and feed in the open ocean, settle in their adult benthic habitat. This shift is particularly dramatic in coral‐reef fishes, where the adult habitat is immensely complex. However, whether the adult trophic ecotype affects the morphology of early‐life stages is unclear. We measured a suite of 26 functional‐morphological traits in the head and body of larvae from an ontogenetic series of 16 labrid species. Using phylogenetic comparative methods, we reconstructed the location of adaptive peaks of larvae whose adults are associated with different trophic ecotypes. We found that the morphospace occupation in these larvae is largely driven by divergent adaptations to the adult benthic habitats. The disparity between adaptive peaks is achieved early and does not monotonically increase with size. Our findings thus refute the notion that larvae rapidly acquire the trophic‐specific traits during a metamorphic period immediately prior to settlement. This early specialization might be due to the highly complex musculoskeletal system of the head that cannot be rapidly modified. [ABSTRACT FROM AUTHOR]

Age at sexual maturity is a central life-history parameter, strongly related to key traits such as body size and longevity. It is influenced by environmental and intrinsic factors that affect growth rates and gonad development. Using data on the age at sexual maturity in 123 species of amphibians worldwide, we tested whether sexual maturity is delayed at high altitudes and latitudes, in cold and dry regions and on islands. We further tested whether sexual maturity is delayed in species with parental care and direct development (no tadpole stage). Using phylogenetic regression and correcting for body size, we found a positive relationship between latitude and sexual maturity. Surprisingly, altitude was negatively correlated with sexual maturity in small species. Temperature was negatively related to sexual maturity in females but not in males. Precipitation and seasonality did not effect on either sex. Species that engage in parental care or have direct-developing larvae mature early. We found no effect of insularity, contradicting the insular syndrome hypothesis. Meta-analyses revealed that, within species, sexual maturity is reached at younger ages in warm temperatures in aseasonal environments and in low altitudes. Thus, although life-history strategies affect maturation time, climate can further delay or accelerate development - probably through effects on metabolic rates and season length.. [ABSTRACT FROM AUTHOR]

Sexual-size dimorphism ( SSD) is widespread in animals. Body length is the most common trait used in the study of SSD in reptiles. However, body length combines lengths of different body parts, notably heads and abdomens. Focusing on body length ignores possible differential selection pressures on such body parts. We collected the head and abdomen lengths of 610 lizard species ( Reptilia: Squamata: Sauria). Across species, males have relatively larger heads, whereas females have relatively larger abdomens. This consistent difference points to body length being an imperfect measure of lizard SSD because it comprises both abdomen and head lengths, which often differ between the sexes. We infer that female lizards of many species are under fecundity selection to increase abdomen size, consequently enhancing their reproductive output (enlarging either clutch or offspring size). In support of this, abdomens of lizards laying large clutches are longer than those of lizards with small clutches. In some analyses, viviparous lizards have longer abdomens than oviparous lizards with similar head lengths. Our data also suggest that male lizards are under sexual selection to increase head size, which is positively related to winning male-male combats and to faster grasping of females. Thus, larger heads could translate into higher probability to mate. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110, 665-673. [ABSTRACT FROM AUTHOR]

Body size and body shape are tightly related to an animal's physiology, ecology and life history, and, as such, play a major role in understanding ecological and evolutionary phenomena. Because organisms have different shapes, only a uniform proxy of size, such as mass, may be suitable for comparisons between taxa. Unfortunately, snake masses are rarely reported in the literature. On the basis of 423 species of snakes in 10 families, we developed clade-specific equations for the estimation of snake masses from snout-vent lengths and total lengths. We found that snout-vent lengths predict masses better than total lengths. By examining the effects of phylogeny, as well as ecological and life history traits on the relationship between mass and length, we found that viviparous species are heavier than oviparous species, and diurnal species are heavier than nocturnal species. Furthermore, microhabitat preferences profoundly influence body shape: arboreal snakes are lighter than terrestrial snakes, whereas aquatic snakes are heavier than terrestrial snakes of a similar length. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●●, ●●-●●. [ABSTRACT FROM AUTHOR]

The tempo andmode of body size evolution on islands are believed to be well known. It is thought that body size evolves relatively quickly on islands toward the mammalian modal value, thus generating extreme cases of size evolution and the island rule. Here, we tested both theories in a phylogenetically explicit context, by using two different species-level mammalian phylogenetic hypotheses limited to sister clades dichotomizing into an exclusively insular and an exclusively mainland daughter nodes. Taken as a whole, mammals were found to show a largely punctuational mode of size evolution. We found that, accounting for this, and regardless of the phylogeny used, size evolution on islands is no faster than on the continents. We compared different selection regimes using a set of Ornstein-Uhlenbeck models to examine the effects of insularity of the mode of evolution. The models strongly supported clade-specific selection regimes. Under this regime, however, an evolutionary model allowing insular species to evolve differently from their mainland relatives performs worse than a model that ignores insularity as a factor. Thus, insular taxa do not experience statistically different selection from their mainland relatives. [ABSTRACT FROM AUTHOR]

Extreme morphologies of many insular taxa suggest that islands have unusual properties that influence the tempo and mode of evolution. Yet whether insularity per se promotes rapid phenotypic evolution remains largely untested. We extend a phylogenetic comparative approach to test the influence of novel environments versus insularity on rates of body size and sexual size dimorphism diversification in Anolis. Rates of body size diversification among small-island and mainland species were similar to those of anole species on the Greater Antilles. However, the Greater Antilles taxa that colonized small islands and the mainland are ecologically nonrandom: rates of body size diversification among small-island and mainland species are high compared to their large-island sister taxa. Furthermore, rates of diversification in sexual size dimorphism on small islands are high compared to all large-island and mainland lineages. We suggest that elevated diversifying selection, particularly as a result of ecological release, may drive high rates of body size diversification in both small-island and mainland novel environments. In contrast, high abundance (prevalent among small-island lizard communities) mediating intraspecific resource competition and male–male competition may explain why sexual size dimorphism diversifies faster among small-island lineages than among their mainland and large-island relatives. [ABSTRACT FROM AUTHOR]

The island rule is the phenomenon of the miniaturization of large animals and the gigantism of small animals on islands, with mammals providing the classic case studies. Several explanations for this pattern have been suggested, and departures from the predictions of this rule are common among mammals of differing body size, trophic habits, and phylogenetic affinities. Here we offer a new explanation for the evolution of body size of large insular mammals, using evidence from both living and fossil island faunal assemblages. We demonstrate that the extent of dwarfism in ungulates depends on the existence of competitors and, to a lesser extent, on the presence of predators. In contrast, competition and predation have little or no effect on insular carnivore body size, which is influenced by the nature of the resource base. We suggest dwarfism in large herbivores is an outcome of the fitness increase resulting from the acceleration of reproduction in low-mortality environments. Carnivore size is dependent on the abundance and size of their prey. Size evolution of large mammals in different trophic levels has different underlying mechanisms, resulting in different patterns. Absolute body size may be only an indirect predictor of size evolution, with ecological interactions playing a major role. [ABSTRACT FROM AUTHOR]

We compared incubation and fledging times between large (> 2 kg) migrating and sedentary birds. We found that while length of incubation period does not differ between migrants and nonmigrants, fledging period is significantly shorter in the former. This pattern is apparent in the class as a whole, as well as within orders, families, and genera. Additional, albeit weak, evidence suggests that clutch sizes of migrants are smaller than those of closely related resident birds. We hypothesize that the need to migrate constrains the length of developmental period of large migrating birds, especially in species that undertake long-distance migration. [ABSTRACT FROM AUTHOR]

Studies of Bergmann's rule may encompass a non-random subsample of extant homeotherms. We examined patterns of correlation between skull length and geographical latitude in 44 species of carnivores in order to test the validity of Bergmann's rule in the Carnivora. Results were then compared to those of other studies. Significant positive correlation between skull length and latitude was found in 50% of carnivore species, while significant negative correlation was found in only 11% of species. These results indicate that the occurrence of Bergmann's rule in the Carnivora is less frequent than earlier published data suggest. Publication bias is not detected in published data. Therefore, previous studies of geographical size variation might be biased in favour of species known to follow Bergmann's rule. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81, 579–588. [ABSTRACT FROM AUTHOR]

Most species remain unknown to science and might go extinct before we recognize their existence. Although specimens belonging to many of these unknown taxa may already be housed in scientific collections, they can remain 'shelved' for years bearing the wrong name or without a formal name. We investigate factors underlying variation in time lag between collection and description dates for 2356 reptile species described worldwide between 1992 and 2017. We modelled the time to description using biological and sociological variables in a time-to-event analysis. Time lag between collection and description varied from zero to 155 years (median = 5). More than one-quarter of species involved specimens 'shelved' for 12 years or more. The time lag was shorter when the collector of the holotype – specimen serving as the name-bearer of the species – was an author of the description, while taxonomic revisions uncovered species with longer time lags. Unknown species collected by non-taxonomists and 'shelved' in scientific collections remained incorrectly identified for a much longer time. Taxonomic revisions are crucial to reverse this trend and improve benefits of the collecting performed by non-taxonomists. Our findings reveal the kinds of preserved reptile specimens that most likely represent unknown species in scientific collections. [ABSTRACT FROM AUTHOR]

Based on a comprehensive literature survey, we determined the sources of the terrestrial vertebrate species on Christmas Island, asking where they originated relative to Wallace's Line (the southern end of the divide lies 1100 km to the east, where the Lombok Strait adjoins the eastern Indian Ocean). The two bats, Pipistrellus murrayi and Pteropus natalis , are from the west. Concerning the endemic and 'resident' bird species, one is from the west (Collocalia natalis), four are from the east (Accipiter fasciatus , Egretta novaehollandiae , Falco cenchroides and Ninox natalis) and the other 15 are ambiguous or indeterminate. Most of the land-locked species are also from the east: rodents Rattus macleari and Rattus nativitatis , and squamates Cryptoblepharus egeriae , Emoia nativitatis and Lepidodactylus listeria. Additionally, two have westerly origins (Crocidura trichura and Cyrtodactylus sadleiri), one is ambiguous (Emoia atrocostata) and another is unknown (Ramphotyphlops exocoeti). West-directed surface currents that flow across the eastern Indian Ocean towards Christmas Island would have facilitated most of the land-animal colonizations. We therefore suggest that Wallace's Line be redrawn such that the landmass is placed on the Australasian side of this fundamental biogeographical boundary. [ABSTRACT FROM AUTHOR]

Many animals have strict diel activity patterns, with unique adaptations for either diurnal or nocturnal activity. Diel activity is phylogenetically conserved, yet evolutionary shifts in diel activity occur and lead to important changes in an organism's morphology, physiology, and behavior. We use phylogenetic comparative methods to examine the evolutionary history of diel activity in skinks, one of the largest families of terrestrial vertebrates. We examine how diel patterns are associated with microhabitat, ambient temperatures, and morphology. We found support for a nondiurnal ancestral skink. Strict diurnality in crown group skinks only evolved during the Paleogene. Nocturnal habits are associated with fossorial activity, limb reduction and loss, and warm temperatures. Our results shed light on the evolution of diel activity patterns in a large radiation of terrestrial ectotherms and reveal how both intrinsic biotic and extrinsic abiotic factors can shape the evolution of animal activity patterns. [ABSTRACT FROM AUTHOR]

The skink genus Lobulia is endemic to New Guinea, the largest and highest tropical island in the world. Lobulia and its related genera represent an important component of the montane herpetofauna of New Guinea, but it remains understudied and poorly known. We here provide the first, large-scale, systematic revision of Lobulia , using molecular phylogenetic and morphological comparisons to assess the monophyly of the genus and the diversity of species within it. We find that Lobulia , as currently defined, is polyphyletic. The eight species currently assigned to it form three clades. Furthermore, many specimens from New Guinea of unknown specific affinity are genetically and morphologically distinct from each other. Based on these data, we re-diagnose Lobulia and two of its closely related genera, Prasinohaema and Papuascincus. We erect four new genera (Alpinoscincus gen. nov. Nubeoscincus gen. nov. Ornithuroscincus gen. nov. and Palaia gen. nov.) to address the problem of polyphyly and describe nine new species Lobulia fortis sp. nov. Lobulia huonensis sp. nov. Loublia marmorata sp. nov. Lobulia vogelkopensis sp. nov. Ornithuroscincus bengaun sp. nov. Ornithuroscincus inornatus sp. nov. Ornithuroscincus pterophilus sp. nov. Ornithuroscincus shearmani sp. nov. and Ornithuroscincus viridis sp. nov. We supplement this taxonomic revision by investigating the biogeographic history of Lobulia s.l. and find evidence for a large radiation in the accreted terranes of New Guinea, with multiple independent colonizations of montane habitats and subsequent recolonization of lowland habitats. Our study reinforces the uniqueness and richness of the montane herpetofauna of New Guinea and the importance of mountains to biodiversity in the Tropics. [ABSTRACT FROM AUTHOR]

Populations of the same species occupying different microhabitats can either exhibit generalized traits across them or display intraspecific variability, adapting to each microhabitat in order to maximize performance. Intraspecific variability contributes to the generation of diversity, following selection and adaptation, and understanding such variability is important for comprehending how individuals choose their microhabitats. Compared with interspecific variability, however, intraspecific variability in functional morphology and its relationship with microhabitat preference and use have been relatively little studied. Here we examined whether populations of the gecko Mediodactylus kotschyi that differ in the substrates they occupy display habitat-specific behaviors and differing morphologies associated with functional adaptation to their microhabitats. We collected 207 geckos from under or on rocks or on trees from seven populations in Greece. On large islands individuals occupy both substrates; whereas small islets are devoid of trees and the geckos are restricted to rocks, while on the mainland they are only found on trees. We determined gecko substrate preferences in the laboratory, together with their clinging abilities to the different substrates. We measured their limbs, digits, and claws and assessed how these measurements relate to clinging ability. Geckos from all populations preferred the tree made available to them, but this preference was not statistically significant. Geckos from both large and small islands clung better to the tree than to the rock in the laboratory, while those from the mainland clung similarly to both substrates. Geckos collected from trees had longer manual digits and hind limbs. Geckos collected from large and small islands had taller (longer on the dorso-ventral axis; henceforth "deeper") claws. Longer digits and deeper but shorter claws were associated with a better ability to cling to rocks. Our findings suggest that while M. kotschyi is potentially preferentially arboreal, due to the great variation and plasticity it possesses, it can successfully also exploit the habitats available on the smallest, treeless islets in the Aegean Sea. Our study suggests that the dichotomous use of generalist versus specialist in describing species' habitat use is oversimplified, and we suggest the use of a generalist–specialist gradient instead. [ABSTRACT FROM AUTHOR]

Insular animals are thought to be under weak predation pressure and increased intraspecific competition compared with those on the mainland. Thus, insular populations are predicted to evolve 'slow' life histories characterized by fewer and smaller clutches of larger eggs, a pattern called the 'island syndrome'. To test this pattern, we collected data on egg volume, clutch size and laying frequency of 31 Aegean Island populations of the closely related geckos of the Mediodactylus kotschyi species complex. We tested how predation pressure, resource abundance, island area and isolation influenced reproductive traits. Isolation and predation were the main drivers of variation in life-history traits. Higher predator richness seemed to promote faster life histories, perhaps owing to predation on adults, whereas the presence of boas promoted slower life histories, perhaps owing to release from predation by rats on the eggs of geckos. Insular geckos followed only some of the predictions of the 'island syndrome'. Predation pressure seemed to be more complex than expected and drove life histories of species in two opposing directions. Our results highlight the importance of considering the identity of specific predators in ecological studies. [ABSTRACT FROM AUTHOR]

An aquatic animal faces challenges not encountered by its terrestrial counterparts, promoting adaptive responses in multiple traits. For example, a thicker dermis might protect snakes when they are pushed against sharp objects by water currents, and might enable a snake to shed fouling organisms attached to its skin. We thus predicted that marine snakes should have thicker skin than terrestrial species, and that smaller sea snakes should have relatively thicker skin (because absolute, not relative, thickness determines vulnerability to fouling). Measurements of 192 snakes of 44 species supported those predictions. Many (but not all) sea snakes have skins 50% thicker than those of terrestrial and amphibious snake species, representing multiple independent evolutionary origins of thicker skin (in acrochordids, Laticauda sea kraits and both main clades of hydrophiine sea snakes). Marine snakes showed different allometries of skin thickness compared with their terrestrial counterparts; larger snakes had thicker skin within and among species of amphibious and terrestrial snakes, but larger aquatic snake species had thinner skin compared with smaller taxa. Interspecific variation in skin thickness was primarily due to increased collagen in the deep dermis, a physical barrier well suited to protecting against physical injury and to resisting penetration by epibionts. [ABSTRACT FROM AUTHOR]

Animal lifespan is determined by extrinsic and intrinsic factors causing mortality. According to the evolutionary theories of senescence, when mortality pressures are low, animals delay reproduction. This enables species to grow more slowly and, consequently, natural selection can act against harmful mutations in adulthood, thereby increasing lifespans. To test predictions of these theories we assembled a dataset on the maximum longevities and relevant ecological variables of 1320 reptilian species. Correcting for phylogeny, we modelled the link between reptile longevity and factors such as body size, microhabitat, activity period, insularity, annual temperature, temperature seasonality, elevation and clutch size that we hypothesized will affect extrinsic mortality rates and hence lifespan. Body mass explained a small proportion of the variance in reptile longevity. Species living on islands, and in colder and more seasonal environments, lived longer. Observed maximum longevity was positively associated with the number of individuals used to estimate it. Our results suggest that species exposed to reduced extrinsic and intrinsic mortality pressures (lower predation, lower metabolic rates and shorter activity periods) live longer. Sampling more individuals increases the chances of finding older specimens and should be corrected for when studying maximum longevity. [ABSTRACT FROM AUTHOR]

An efficient digestive system is of pivotal importance for survival as it governs the energy flow from the environment to organisms. Reptiles require relatively little energy, and their digestive system can readily respond to internal and external shifts. Ergo, reptiles can colonize even demanding habitats by improving digestive performance. Although many studies address lizard digestion, few examine geographical variation. Here, we examine how the digestion of a single lizard species (Stellagama stellio) differs along a latitudinal and climatic gradient, comprising mainland and insular populations. Apparent digestive efficiency (ADE, the percentage of ingested energy absorbed through the gut) for lipids, proteins and sugars was used to answer the main question: is digestive performance consistent across populations (one species, one pattern) or is it dependent on habitat features (different populations, different patterns). We expected that climate and insularity would affect ADE. Indeed, the northernmost populations, inhabiting colder, rainier, less seasonal regions, achieved the lower ADEs. Insularity, however, had no effect on digestive efficiency, indicating that insular (or mainland) habitats are not all the same and local particularities may play a role. These findings suggest that each population adjusts its physiological repertoire to the local conditions. [ABSTRACT FROM AUTHOR]

Acanthodactylus is a widespread lacertid genus occurring from the Iberian Peninsula and western North Africa to western India including the Middle East, Cyprus, and the Arabian Peninsula. The genus is in dire need of a taxonomic revision, and the phylogenetic relationships amongst and within its species remain unclear. In particular, the taxonomy and relationship of the allopatric, narrow-ranged Acanthodactylus schreiberi and its close relative, the widespread Acanthodactylus boskianus asper, are poorly understood. We estimated the phylogenetic and phylogeographical structure of A. schreiberi across its distribution range, and evaluated its relationships to A. b. asper, using mitochondrial and nuclear data. The phylogenetic results indicate that both species are paraphyletic, with A. schreiberi nested within A. b. asper, and the subspecies A. schreiberi syriacus nested within a distinct lineage of A. b. asper. We suggest that the group is in need of a taxonomic revision because the identified lineages and genetic diversity are incongruent with the currently recognized taxonomy. We tentatively conclude that A. schreiberi is restricted to Cyprus and Turkey, reduced to a single form, and that the populations in Lebanon and Israel belong to A. b. asper. © 2014 The Linnean Society of London [ABSTRACT FROM AUTHOR]