Biogeographic patterns of the East African coastal forest vertebrate fauna

Abstract

The archipelago-like coastal forest of East Africa is one of the highest priority ecosystems for biodiversity conservation worldwide. Here we investigate patterns of species richness and biogeographic distribution among birds, mammals and reptiles of these forests, using distribution data obtained from recently published reviews and information collated by the WWF Eastern Africa Coastal Forest Ecoregion Programme. Birds and mammals species were divided into forest specialists and generalists, and forest specialist reptiles into 'coastal' and 'forest' endemics. The species richness of birds and generalist mammals increased with area, and is probably a result of area-dependent extinction. Only in birds, however, species richness increased with decreasing isolation, suggesting possible isolation-dependent colonization. Forest diversity, associated to altitudinal range, is important for specialist birds and mammals, whose species richness increased with wider altitudinal range. The number of relict coastal endemic and forest endemic reptiles was higher in forests with wider altitudinal ranges and on relatively higher altitude, respectively. Such forests have probably provided a suitable (and perhaps stable) environment for these species through time, thus increasing their persistence. Parsimony 123Biodivers Conserv DOI 10.1007/s10531-006-9022-0 analysis of distributions (PAD) and cluster analyses showed geographical distance and general ecological similarity among forests as a determinant factor in bird distribution patterns, with compositional similarity decreasing with increasing inter-forest distance. Compositional similarity patterns of mammals among the forests did not show a strong geographical correspondence or a significant correlation with inter-forest distance, and those of reptiles were not resolved, with very low similarity levels among forest faunas. Our results suggest that the relative importance (and causal relationship) of forest attributes affecting the distribution of the East African coastal forest vertebrate fauna varies depending on life history traits such as dispersal ability and forest specialization. The groupings in PAD are partly congruent with some of the previous classifications of areas of endemism for this region, supporting the 'naturalness' of these regions.

Using biodiversity deconstruction to disentangle assembly and diversity dynamics of understorey plants along post‐fire succession in boreal forest

“…There is a growing body of evidence demonstrating the usefulness of the approach in disentangling distinct distribution patterns among species groups, and for understanding the presence or absence of underlying processes (Marquet et al ., 2004; Blamires et al ., 2007; Terribile et al ., 2009; Azeria et al ., 2009a). Different criteria could be applied to deconstruct assemblages, from those based on: (1) prior knowledge of habitat use (Azeria et al ., 2007; Blamires et al ., 2007); (2) ‘guilds’ or multiple species‐specific characteristics (Mac Nally et al ., 2008; Wiens et al ., 2008); or (3) combinations of macroecological traits, such as range size and phylogenetic structure (Terribile et al ., 2009). All of the above are valid in their own right, but often require detailed information on species‐specific traits.…”

Vanishing refuge? Testing the forest refuge hypothesis in coastal East Africa using genome‐wide sequence data for seven amphibians

“…Previous species richness and endemism studies in the CFEA have recognized the existence of a biogeographic division situated between the northern (Zanzibar) and southern (Inhambane) Zanzibar‐Inhambane ecoregions (Azeria et al., ; Burgess et al., , , ). Together, our analyses across taxa lend support to this division, with congruent divergences between southern populations in Mozambique, Zimbabwe and Malawi, and the remaining CFEA regions in Tanzania and Kenya.…”

“…Historical environmental change across tropical East Africa has been frequent since the Miocene, and the current CFEA are considered to be the remnants of a once continuous forest that has expanded and contracted for the past 40 million years (Axelrod & Raven, ; Demenocal, ; Maslin et al., ; Mumbi, Marchant, Hooghiemstra, & Wooller, ). Combined knowledge of endemism patterns and environmental change have led to the assumption that current CFEA biodiversity mainly originated from the isolation and persistence of ancient lineages in forest refugia, with local extinctions and in some cases adaptation to non‐forest habitats across the rest of the region (Azeria, Sanmartín, Ås, Carlson, & Burgess, ; Barratt et al., 2017a; Burgess et al., ). The coastal forests have thus been described as a “vanishing refuge” (Burgess et al., ), although to date forest refugial processes have not been thoroughly tested against alternative modes of diversification (Damasceno, Strangas, Carnaval, Rodrigues, & Moritz, ; Kirschel et al., ; Schneider et al., ; Zhen et al., ).…”

Muhaka icipe, an enigmatic new genus and species of Kleidotomini (Hymenoptera: Figitidae: Eucoilinae) from an East African coastal forest

“…Additionally, various projects have focused on, or included data from, Muhaka Forest, including studies on dendrolimnetic (treehole) Odonata (Clausnitzer 2002;Clausnitzer and Lindeboom 2002), Lepidoptera biodiversity (Rogo and Odulaja 2001;Lehmann and Kioko 2005), fly pollination of Ceropegia (Apocynaceae: Asclepiadoideae) (Masinde 2004), vertebrate distribution in coastal forests (Azeria et al 2007), and species richness of birds in Kenyan coastal forests (Waiyaki and Bennun 2000).…”