Paths to annihilation: Genetic and demographic consequences of range contraction patterns

ABSTRACTSpecies range contractions are important contributors to biological annihilation, yet typically do not receive the same attention as extinctions. Range contractions can lead to marked impacts on populations but are often only characterized by measurements of reduced extent. For effective conservation efforts, it is critical to recognize that not all range contractions are the same. We propose four distinct patterns of range contraction: shrinkage, amputation, hollow, and fragmentation. We tested their impact on populations of a generic generalist species using forward-time simulations. Results showed that all four patterns differentially reduced population abundance (declines of 60-80%) and significantly increased average relatedness, with differing patterns in nucleotide diversity (π) declines relative to the contraction pattern. The fragmentation pattern resulted in the strongest effects on post-contraction genetic diversity and structure. Defining and quantifying range contraction patterns and their consequences for the planet’s biodiversity provides necessary information to combat biological annihilation in the Anthropocene.

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Response of xerophytic plants to glacial cycles in southern South America

Annals of Botany ◽

10.1093/aob/mcy235 ◽

2019 ◽

Vol 124 (1) ◽

pp. 15-26 ◽

Cited By ~ 1

Author(s):

Carmen G Ossa ◽

Paz Montenegro ◽

Isabel Larridon ◽

Fernanda Pérez

Keyword(s):

Genetic Diversity ◽

Isolation By Distance ◽

Population History ◽

Arid Environments ◽

Glacial Cycles ◽

Niche Modelling ◽

Climatic Niche ◽

Range Contraction ◽

Genetic Diversity And Structure ◽

Semi Arid

Abstract Background and Aim Quaternary glaciations strongly affected the distribution of species from arid and semi-arid environments, as temperature drops were accompanied by strong fluctuations in rainfall. In this study, we examined the response of xerophytic species to glacial cycles, determining the genetic patterns and climatic niche of Echinopsis chiloensis var. chiloensis, an endemic columnar cactus of arid and semi-arid regions of Chile. Methods We analysed 11 polymorphic microsatellites for 130 individuals from 13 populations distributed across the entire distribution of the species. We examined genetic diversity and structure, identified possible patterns of isolation by distance (IBD) and tested two competing population history scenarios using Approximate Bayesian Computation. The first scenario assumes a constant population size while the second includes a bottleneck in the southern population. The latter scenario assumed that the southernmost populations experienced a strong contraction during glaciation, followed by a postglacial expansion; by contrast, the area of the northernmost populations remained as a stable refugium. We also used ecological niche modelling (ENM) to evaluate the location and extension of suitable areas during the Last Glacial Maximum (LGM) and the mid-Holocene. Key Results We found a decline in genetic diversity towards high latitudes and a significant IBD pattern that together with ENM predictions suggest that E. chiloensis var. chiloensis experienced range contraction northwards during wet–cold conditions of the LGM, followed by expansion during aridification of the mid-Holocene. In addition to IBD, we detected the presence of a strong barrier to gene flow at 32°30′S, which according to coalescence analysis occurred 44 kyr BP. The resulting genetic clusters differed in realized climatic niche, particularly in the variables related to precipitation. Conclusions Our results suggest that the cactus E. chiloensis var. chiloensis experienced range contraction and fragmentation during the wet–cold conditions of the LGM, which may have facilitated ecological differentiation between northern and southern populations, promoting incipient speciation.

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Genetic diversity and population structure of Plasmodium falciparum in Nigeria: insights from microsatellite loci analysis

Malaria Journal ◽

10.1186/s12936-021-03734-x ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Fehintola V. Ajogbasile ◽

Adeyemi T. Kayode ◽

Paul E. Oluniyi ◽

Kazeem O. Akano ◽

Jessica N. Uwanibe ◽

...

Keyword(s):

Genetic Diversity ◽

Plasmodium Falciparum ◽

Population Structure ◽

Microsatellite Loci ◽

Control Strategies ◽

Population Diversity ◽

Parasite Population ◽

Nested Polymerase Chain Reaction ◽

Public Health Burden ◽

Genetic Diversity And Structure

Abstract Background Malaria remains a public health burden especially in Nigeria. To develop new malaria control and elimination strategies or refine existing ones, understanding parasite population diversity and transmission patterns is crucial. Methods In this study, characterization of the parasite diversity and structure of Plasmodium falciparum isolates from 633 dried blood spot samples in Nigeria was carried out using 12 microsatellite loci of P. falciparum. These microsatellite loci were amplified via semi-nested polymerase chain reaction (PCR) and fragments were analysed using population genetic tools. Results Estimates of parasite genetic diversity, such as mean number of different alleles (13.52), effective alleles (7.13), allelic richness (11.15) and expected heterozygosity (0.804), were high. Overall linkage disequilibrium was weak (0.006, P < 0.001). Parasite population structure was low (Fst: 0.008–0.105, AMOVA: 0.039). Conclusion The high level of parasite genetic diversity and low population structuring in this study suggests that parasite populations circulating in Nigeria are homogenous. However, higher resolution methods, such as the 24 SNP barcode and whole genome sequencing, may capture more specific parasite genetic signatures circulating in the country. The results obtained can be used as a baseline for parasite genetic diversity and structure, aiding in the formulation of appropriate therapeutic and control strategies in Nigeria.

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