4 results on '"Tim I. Morley"'
Search Results
2. Components of micro-evolutionary and phenotypic change in seasonal migration versus residence in a wild population
- Author
-
Paul Acker, Francis Daunt, Sarah Wanless, Sarah J. Burthe, Mark A. Newell, Michael P. Harris, Robert L. Swann, Carrie Gunn, Tim I. Morley, and Jane M. Reid
- Abstract
Dissecting joint micro-evolutionary and plastic responses to environmental perturbations fundamentally requires quantifying interacting components of genetic and environmental variation underlying expression of key traits. This ambition is particularly challenging for phenotypically discrete traits where multiscale decompositions are required to handle non-linear transformations of underlying genetic and environmental variation into phenotypic variation, especially when effects have to be estimated from incomplete field observations. We devised a novel joint multistate capture-recapture and quantitative genetic animal model, and fitted this model to full-annual-cycle resighting data from partially migratory European shags (Gulosus aristotelis) to estimate key components of genetic, environmental and phenotypic variance in the ecologically critical discrete trait of seasonal migration versus residence. We demonstrate non-trivial additive genetic variance in latent liability for migration, resulting in estimated micro-evolutionary responses following two episodes of strong survival selection. Yet, underlying additive genetic effects interacted with substantial permanent individual and temporary environmental effects to generate complex non-additive effects, causing large intrinsic gene-by-environment interaction variance in phenotypic expression. Our findings reveal how temporal dynamics of seasonal migration result from combinations of instantaneous micro-evolution and within-individual phenotypic inertia, and highlight how plastic phenotypic variation could expose cryptic genetic variation underlying discrete traits to complex forms of selection.
- Published
- 2022
3. Cold comfort: Arctic seabirds find refugia from climate change and potential competition in marginal ice zones and fjords
- Author
-
Erpur Snær Hansen, Aude Boutet, Tanguy Deville, Thomas Lundgaard Hansen, Derren Fox, Thomas Larsen, Patrick Roberts, Anne-Sophie Bonnet-Lebrun, Fabrice le Bouard, Thorkell Lindberg Thórarinsson, Norman Ratcliffe, Tim I. Morley, Morten Frederiksen, and Yann Kolbeinsson
- Subjects
0106 biological sciences ,media_common.quotation_subject ,Climate Change ,Geography, Planning and Development ,Population ,Foraging ,Sea ice ,Climate change ,Refugia ,Fjords ,010603 evolutionary biology ,01 natural sciences ,Competition (biology) ,Charadriiformes ,Niche partitioning ,Uria aalge ,Temperate climate ,Environmental Chemistry ,Animals ,Ice Cover ,14. Life underwater ,education ,Ecosystem ,media_common ,education.field_of_study ,Ecology ,biology ,Competition ,Arctic Regions ,010604 marine biology & hydrobiology ,Ice ,General Medicine ,15. Life on land ,biology.organism_classification ,Geography ,Arctic ,Refugium ,13. Climate action ,Uria lomvia ,Changing Arctic Ocean ,Estuaries - Abstract
Climate change alters species distributions by shifting their fundamental niche in space through time. Such effects may be exacerbated by increased inter-specific competition if climate alters species dominance where competitor ranges overlap. This study used census data, telemetry and stable isotopes to examine the population and foraging ecology of a pair of Arctic and temperate congeners across an extensive zone of sympatry in Iceland, where sea temperatures varied substantially. The abundance of Arctic Brünnich’s guillemot Uria lomvia declined with sea temperature. Accessibility of refugia in cold water currents or fjords helped support higher numbers and reduce rates of population decline. Competition with temperate Common guillemots Uria aalge did not affect abundance, but similarities in foraging ecology were sufficient to cause competition when resources are limiting. Continued warming is likely to lead to further declines of Brünnich’s guillemot, with implications for conservation status and ecosystem services. Introduction Methods - Study sites - Data collection - Stable isotope analysis - Data analysis Results - Patterns of abundance in relation to SST - Foraging distribution, range and habitat use - Stable isotope ratios Discussion Conclusion - Societal and policy implications
- Published
- 2022
4. Long-term inter- and intraspecific dietary variation in sibling seabird species
- Author
-
William F. Mills, Tim I. Morley, Richard A. Phillips, and Stephen C. Votier
- Subjects
0106 biological sciences ,education.field_of_study ,Ecology ,biology ,010604 marine biology & hydrobiology ,Southern giant petrel ,Population ,Arctocephalus gazella ,Zoology ,Aquatic Science ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Giant petrel ,Procellariiformes ,Antarctic krill ,biology.animal ,Fur seal ,Seabird ,education ,Ecology, Evolution, Behavior and Systematics - Abstract
Northern Macronectes halli and southern giant petrels M. giganteus are opportunistic predators and the dominant avian scavengers in sub-Antarctic and Antarctic ecosystems. At South Georgia, there are globally important breeding populations of both species; however, no detailed diet study has been carried out at this site for > 35 years. Here, we analysed stomach contents of northern (n = 81) and southern giant petrel (n = 73) chicks at Bird Island, South Georgia (2014/15–2016/17). Specifically, we investigated: (1) interspecific and sexual dietary segregation; (2) diet changes within and among recent years; and (3) long-term diet changes since 1979/80–1980/81. Overall diet composition was similar between species, with penguins comprising approximately half the diet by mass. In both species (but more pronounced in southern giant petrels), prey delivered by female parents included higher proportions (by mass) of penguins and Antarctic krill Euphausia superba, and by male parents included more Antarctic fur seal Arctocephalus gazella carrion and seabirds other than penguins. Consumption of penguins increased, and of seal carrion declined, as chick-rearing progressed, mirroring the decreasing availability of the latter after the peak pupping period in December at South Georgia. Comparisons with data from 1979/80–1980/81 suggest some changes in giant petrel diets; however, these differences were no greater than the typical annual variation, and there were no clear links between diet and breeding allochrony or the differing population trends (more rapid increase in northern than southern giant petrels). The high diet diversity and ability of giant petrels to exploit both carrion and marine prey facilitates coexistence with other sympatric Procellariiformes and explains their favourable population status.
- Published
- 2021
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.