The Last Glacial Maximum

Evolution and population genetic structure of marine species across the Caribbean Sea are shaped by two complex factors: the geological history and the present pattern of marine currents. Characterizing and comparing the genetic structures of codistributed species, such as host–parasite associations, allow discriminating the relative importance of environmental factors and life history traits that influenced gene flow and demographic events. Using microsatellite and Cytochrome Oxidase I markers, we investigated if a host–parasite pair (the heart urchin Meoma ventricosa and its parasitic pea crab Dissodactylus primitivus) exhibits comparable population genetic structures in the Caribbean Sea and how the observed patterns match connectivity regions from predictive models and other taxa. Highly contrasting patterns were found: the host showed genetic homogeneity across the whole studied area, whereas the parasite displayed significant differentiation at regional and local scales. The genetic diversity of the parasitic crabs (both in microsatellites and COI) was distributed in two main groups, Panama–Jamaica–St Croix on the one hand, and the South‐Eastern Caribbean on the other. At a smaller geographical scale, Panamanian and Jamaican parasite populations were genetically more similar, while more genetic differentiation was found within the Lesser Antilles. Both species showed a signature of population expansion during the Quaternary. Some results match predictive models or data from previous studies (e.g., the Western‐Eastern dichotomy in the parasite) while others do not (e.g., genetic differentiation within the Lesser Antilles). The sharp dissimilarity of genetic structure of these codistributed species outlines the importance of population expansion events and/or contrasted patterns of gene flow. This might be linked to differences in several life history traits such as fecundity (higher for the host), swimming capacity of larval stages (higher for the parasite), and habitat availability (higher for the host).

Section: Introductionmentioning

confidence: 99%

Highly contrasted population genetic structures in a host–parasite pair in the Caribbean Sea

Jossart

Ridder

Lessios

et al. 2017

“…Because the climatic conditions were favorable for both willow grouse and rock ptarmigan populations to increase but the PSMC trajectories of all but the Siberian willow grouse indicate a bottleneck during this period, it reveals that the population crash must have been the result of other demographic reasons. And since the geographic regions where these samples come from were either glaciated during the LGM (Greenland, Iceland, Scandinavia and Britain; Clark et al., 2009; Clark & Mix, 2002) or were separated from the remainder of their distribution prior to the LGM (Alaska; Holder et al., 2000), these bottleneck most likely indicate the recolonization of these parts upon termination of the LGM and the creation of the Beringian land bridge, respectively. However, again we advise caution when interpreting recent changes in N e (i.e., the plateaued lines in the PSMC plot from ~60 kya to the present) as they generally indicate the moment when PSMC loses power.…”

Section: Discussionmentioning

confidence: 99%

Past and potential future population dynamics of three grouse species using ecological and whole genome coalescent modeling

Kozma

Lillie

Benito

et al. 2018

Studying demographic history of species provides insight into how the past has shaped the current levels of overall biodiversity and genetic composition of species, but also how these species may react to future perturbations. Here we investigated the demographic history of the willow grouse (Lagopus lagopus), rock ptarmigan (Lagopus muta), and black grouse (Tetrao tetrix) through the Late Pleistocene using two complementary methods and whole genome data. Species distribution modeling (SDM) allowed us to estimate the total range size during the Last Interglacial (LIG) and Last Glacial Maximum (LGM) as well as to indicate potential population subdivisions. Pairwise Sequentially Markovian Coalescent (PSMC) allowed us to assess fluctuations in effective population size across the same period. Additionally, we used SDM to forecast the effect of future climate change on the three species over the next 50 years. We found that SDM predicts the largest range size for the cold‐adapted willow grouse and rock ptarmigan during the LGM. PSMC captured intraspecific population dynamics within the last glacial period, such that the willow grouse and rock ptarmigan showed multiple bottlenecks signifying recolonization events following the termination of the LGM. We also see signals of population subdivision during the last glacial period in the black grouse, but more data are needed to strengthen this hypothesis. All three species are likely to experience range contractions under future warming, with the strongest effect on willow grouse and rock ptarmigan due to their limited potential for northward expansion. Overall, by combining these two modeling approaches, we have provided a multifaceted examination of the biogeography of these species and how they have responded to climate change in the past. These results help us understand how cold‐adapted species may respond to future climate changes.

“…We used 19 bioclimatic layers from four time periods for breeding distributions: Present, mid‐Holocene (approximately 6000 years before present (ybp), LGM (21,000 ybp; Clark et al. 2009), and last interglacial (LIG, 120,000 ybp, Otto‐Bliesner et al. 2006) from the WorldClim database (“CCSM” worldclim.org; http://www.worldclim.org/paleo-climate).…”

Section: Methodsmentioning

confidence: 99%

Fluctuating fire regimes and their historical effects on genetic variation in an endangered shrubland specialist

Vázquez‐Miranda

Barr

Farquhar

et al. 2015

The Pleistocene was characterized by worldwide shifts in community compositions. Some of these shifts were a result of changes in fire regimes, which influenced the distribution of species belonging to fire‐dependent communities. We studied an endangered juniper–oak shrubland specialist, the black‐capped vireo (Vireo atricapilla). This species was locally extirpated in parts of Texas and Oklahoma by the end of the 1980s as a result of habitat change and loss, predation, brood parasitism, and anthropogenic fire suppression. We sequenced multiple nuclear loci and used coalescence methods to obtain a deeper understanding of historical population trends than that typically available from microsatellites or mtDNA. We compared our estimated population history, a long‐term history of the fire regime and ecological niche models representing the mid‐Holocene, last glacial maximum, and last interglacial. Our Bayesian skyline plots showed a pattern of historical population fluctuation that was consistent with changing fire regimes. Genetic data suggest that the species is genetically unstructured, and that the current population should be orders of magnitude larger than it is at present. We suggest that fire suppression and habitat loss are primary factors contributing to the recent decline of the BCVI, although the role of climate change since the last glacial maximum is unclear at present.