Evidence of history in explaining diversity patterns in tropical riverine fish

Abstract

Aim Documentation of the ongoing effect of rain forest refuges at the last glacial maximum (LGM) on patterns of tropical freshwater fish diversity.Location Tropical South and Central America, and West Africa. MethodsLGM rain forest regions and species richness by drainage were compiled from published data. GIS mapping was applied to compile drainage area and contemporary primary productivity. We used multiple regression analyses, applied separately for Tropical South America, Central America and West Africa, to assess differences in species richness between drainages that were connected and disconnected to rain forest refuge zones during the LGM. Spatial autocorrelation of the residuals was tested using Moran's I statistic. We added an intercontinental comparison to our analyses to see if a historical signal would persist even when a regional historical effect (climate at the LGM) had already been accounted for.Results Both area and history (contact with LGM rain forest refuge) explained the greatest proportions of variance in the geographical pattern of riverine species richness. In the three examined regions, we found highest richness in drainages that were connected to the rain forest refuges. No significant residual spatial autocorrelation was detected after considering area, primary productivity and LGM rain forest refuges. These results show that past climatic events still affect West African and Latin American regional and continental freshwater fish richness. At the continental scale, we found South American rivers more species-rich than expected on the basis of their area, productivity and connectedness to rain forest refuge. Conversely, Central American rivers were less species-diverse than expected by the grouped model. African rivers were intermediate. Therefore, a historical signal persists even when a regional historical effect (climate at the LGM) had already been accounted for.Main conclusions It has been hypothesized that past climatic events have limited impact on species richness because species have tracked environmental changes through range shifts. However, when considering organisms with physically constrained dispersal (such as freshwater fish), past events leave a perceptible imprint on present species diversity. Furthermore, we considered regions that have comparable contemporary climatic and environmental characteristics, explaining the absence of a productivity effect. From the LGM to the present day (a time scale of 18,000 years), extinction processes should have played a predominant role in shaping the current diversity pattern. By contrast, the continental effects could reflect historical contingencies explained by differences in speciation and extinction rates between continents at higher time scales (millions of years).

Climate change and its implications for Australia's freshwater fish

“…In contrast, the presence of high mountains in the region is likely to have buffered fishes from past climate-change events by maintaining flows through cloud capture, especially in small streams. This hypothesis is consistent with the work of Tedesco et al (2005) who found the highest fish species richness in Central and South American and West African drainages that were connected to rainforest refugia during the last glacial maximum. Increases in the basal elevation of orographic cloud formation of 100 m per degree of warming are predicted, with major implications for flow volumes in upland tropical streams (Still et al 1999).…”

River hydrological seasonality influences life history strategies of tropical riverine fishes

“…Our dataset was restricted within a very narrow latitudinal range (less than 10°), implying little or no affect of cline gradient and productivity (also related to latitude) on species occurrence (Tedesco et al 2005). Furthermore, as both seasonal and less seasonal drainages occur in northern and southern parts of our study area (Lévêque and Paugy 1999), latitudinal gradient could not have produced the observed patterns of demographic strategies or any unwanted spatial correlation in the analyses.…”

“…For instance, the West African rivers that currently display relatively more stable hydrological conditions are those located in historically stable regions (i.e., Pleistocene refuges; Dupont et al 2000). These rivers tend also to have higher species richness (when river size has been accounted for), and higher historical hydrological stability that could have allowed the speciation and/or the persistence of a higher proportion of equilibrium species (Tedesco et al 2005).…”

The influence of habitat structure on fish assemblages in Amazonian streams of Machado river basin

“…Variations in species composition, structure and distribution in fish assemblages has been attributed to area (i.e. basin area, lake surface area), regional net primary production, habitat heterogeneity (Tedesco, Oberdorff, Lasso, Zapata, & Hugueny, 2005), substrate type, microhabitat type and water flow (Mendonça et al, 2005).…”

“…Variations in species composition, structure and distribution in fish assemblages has been attributed to area (i.e. basin area, lake surface area), regional net primary production, habitat heterogeneity (Tedesco, Oberdorff, Lasso, Zapata, & Hugueny, 2005), substrate type, microhabitat type and water flow (Mendonça et al, 2005).Land use plays a key role in shaping the environment on global, regional and local scales (Krusche et al, 2005). Changes in the type of land cover influence the biodiversity and ecosystem services (Foley et al, 2007), global climate (Hartmann et al, 2013), biogeochemical cycles and water cycles (Laudon et al, 2016).…”