Abstract
Landscape heterogeneity, phylogenetic history, and stochasticity all influence patterns of geneflow and connectivity in wild vertebrates. Fine-scale patterns of genetic partitioning may be particularly important for the sustainable management of widespread species in trade, such as crocodiles. We examined genetic variation within the rediscovered African crocodile, Crocodylus suchus, across its distribution in West and Central Africa. We genotyped 109 individuals at nine microsatellite loci from 16 sampling localities and used three Bayesian clustering techniques and an analysis of contemporary gene flow to identify population structure across the landscape. We identified up to eight genetic clusters that largely correspond to populations isolated in coastal wetland systems and across large distances. Crocodile population clusters from the interior were readily distinguished from coastal areas, which were further subdivided by distance and drainage basin. Migration analyses indicated contemporary migration only between closely positioned coastal populations. These findings indicate high levels of population structure throughout the range of C. suchus and we use our results to suggest a role for molecular tools in identifying crocodile conservation units for this species. Further research, including additional sampling throughout the Congo and Niger drainages, would clarify both the landscape connectivity and management of this species.
Highlights
Repeated phylogeographic patterns across diverse taxa are slowly revealing how both deep and recent phylogeographic events have shaped inter- and intraspecific biodiversity across Africa (Cotterill, 2003; Lorenzen, Heller & Siegismund, 2012; Moodley & Bruford, 2007)
There is accumulating evidence suggesting that these environmental and climatic features played a major role in shifting species distributions and genetic subdivision within a wide range of taxa (Allal et al, 2011; Anthony et al, 2012; How to cite this article Cunningham et al (2016), Fine scale patterns of genetic partitioning in the rediscovered African crocodile, Crocodylus suchus (Saint-Hilaire 1807)
Levels of expected heterozygosity (He) ranged from 0.237 to 0.674 and estimates of allelic richness ranged from 1.77 to 3.47 with estimates of genetic diversity across all measures appearing higher in the west of this species range than in the east (Table 2)
Summary
Repeated phylogeographic patterns across diverse taxa are slowly revealing how both deep and recent phylogeographic events have shaped inter- and intraspecific biodiversity across Africa (Cotterill, 2003; Lorenzen, Heller & Siegismund, 2012; Moodley & Bruford, 2007). There is accumulating evidence suggesting that these environmental and climatic features played a major role in shifting species distributions and genetic subdivision within a wide range of taxa (Allal et al, 2011; Anthony et al, 2012; How to cite this article Cunningham et al (2016), Fine scale patterns of genetic partitioning in the rediscovered African crocodile, Crocodylus suchus (Saint-Hilaire 1807). Conservation and management of widespread species can be improved with proper understanding of patterns of intraspecific genetic diversity and the identification of appropriate management units. Distinct population segments and genetic units are at risk of extinction due to ongoing and predicted rates of habitat loss, climate change, and unsustainable utilization (Dowell et al, 2015a; Henschel et al, 2014). A better understanding of patterns of genetic partitioning of Africa’s fauna across its diverse landscapes will, help us better plan species conservation and management
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