Spatial Turnover and Knowledge Gaps for African Chelonians Mirror those of African Small Mammals: Conservation Implications

Abstract

The causes of spatial distribution gaps for a given species may be either both natural (habitat discontinuities) or non-natural (local extinctions, inaccurate knowledge). These species are defined as 'gap species'. We analyzed the country checklists for African chelonians in order to identify both gap species and gap countries. We also compared patterns observed in chelonians with those observed in African small mammals. Species richness was highest in South Africa, Congo, Nigeria, Tanzania, Angola and Ghana, and the countries exchanging the smallest number of species with neighboring countries were South Africa and Congo. The main gap countries were Togo, Benin, and Congo. Moist savannahs, tropical forests, and swamp areas were inhabited by significantly higher numbers of gap species. Body size of gap species was significantly larger than that of non-gap species, possibly due to bush-meat consumption. Increases in the number of gap species per country were significantly correlated between chelonians and small mammals. There was a significantly positive relationship of turnover rates by paired countries between chelonians and rodents as well as between chelonians and insectivores, and the mean turnover rates by country were highest in Sudan and Chad, whereas the whole southern portion of Africa and part of West Africa had low mean turnover rates. The high number of gap species in Congo, Central African Republic (C.A.R.), and Cameroon may be due to suboptimal research, and in Togo and Benin may depend on the Dahomey Gap. The tropical forests and the moist savannahs are the most important habitats for both groups.

Turtles and Tortoises of Togo: Historical Data, Distribution, Ecology, and Conservation

“…Intriguingly, several species of chelonians which are known to occur in the western and in the eastern forest blocks of West Africa (for instance, Pelusios niger) seem to be absent (or nearly so) from Togo and Benin, which appeared among the main ''gap countries'' for African tortoise and turtle research (Luiselli et al 2012b). Togo and Benin are situated across the Dahomey Gap, which represents a natural savannah barrier for forest species that occur in the forest blocks of West and Central Africa (Luiselli et al 2012a(Luiselli et al , 2012b.…”

“…Togo and Benin are situated across the Dahomey Gap, which represents a natural savannah barrier for forest species that occur in the forest blocks of West and Central Africa (Luiselli et al 2012a(Luiselli et al , 2012b.…”

Testudo marginata Schoepff 1793 – Marginated Tortoise, Kraspedochelóna, Breshka Malore, Testuggine MarginataTestudo marginata Schoepff 1793 – Marginated Tortoise, Kraspedochelóna, Breshka Malore, Testuggine Marginata

“…The species has also been listed as occurring in the Maghreb, Libya (Peters 1880;Luiselli et al 2012), possibly due to confusion with T. kleinmanni (Bauer et al 2017). In Algeria, T. marginata (as "la tortue bordée") was reported to be common around Pélissier (currently Sayada, Mostaganem) by the herpetologist Lallemant (Doumergue 1901).…”

Biogeographic analysis of the composition of the mammalian fauna of Togo (West Africa)

“…The forest islands within the Dahomey Gap can therefore be considered centers of endemism for varied fauna and flora (Leaché et al 2020). Unfortunately, there has been a continued shortage of knowledge on vertebrates in the Dahomey Gap countries of West Africa (Amori et al 2011(Amori et al , 2012Luiselli et al 2012).…”