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To examine the influence of climatic extinction filtering during the last glacial maximum (LGM; c. 18,000 yr bp) and of the subsequent recolonization of forest faunas on contemporary assemblage composition in southern African forests. South Africa, Mozambique, Swaziland, Zimbabwe. Data comprised presence/absence by quarter-degree grid cell for forest-dependent and forest-associated birds, non-volant mammals and frogs. Twenty-one forest subregions were assigned to one of three previously identified forest types: Afrotemperate, scarp, and Indian Ocean coastal belt. Differences among forest types were examined through patterns and gradients of species richness and endemism, assemblage similarity, species turnover, and coefficients of species dispersal direction. The influence of contemporary environment on assemblage composition was investigated using partial canonical correspondence analysis. Several alternative biogeographical hypotheses for the recolonization of forest faunas were tested. Afrotemperate faunas are relatively species-poor, have low species turnover, and are unsaturated and infiltrated by generalist species. In northern and central regions, communities are supplemented by recolonization from scarp forest refugia, and among frogs by autochthanous speciation in localized refugia. Scarp faunas are relatively species-rich, contain many forest-dependent species, have high species turnover, and overlap with coastal and Afrotemperate faunas. Coastal forests are relatively species-rich with high species turnover. Afrotemperate communities were affected most by climatic extinction filtering events. Scarp forests were Afrotemperate refugia during the LGM and are a contemporary overlap zone between Afrotemperate and coastal forest. Coastal faunas derive from post-LGM colonization along the eastern seaboard from tropical East African refugia. The greatest diversity is achieved in scarp and coastal forest faunas in northern KwaZulu-Natal province. This historical centre of diversity has influenced the faunal diversity of nearly all other forests in South Africa. The response of vertebrate taxa to large-scale, historical processes is dependent on their relative mobility: forest birds best illustrate patterns resulting from post-glacial faunal dispersal, while among mammals and frogs the legacy of climatic extinction filtering remains stronger.

Question: What is the relative importance of area- and edge-effects on woody seedling diversity in old Afromontane forest fragments? Location: Mistbelt Afromontane forests, KwaZulu-Natal midlands, South Africa. Methods: Woody seedling abundance and species richness in 590 1-m2 plots were sampled at the forest edge (< 10 m from the edge) and interior in 31 old (> 60 a) Afromontane forest fragments (0.05 – 328.5 ha) with closed edges in an ancient grassland matrix. Results: Unlike young (< 20 a) Amazonian fragments, there was no edge- or area-effect on sample plot seedling density and species richness, although these increased significantly with increasing herb cover (less disturbance). Seedling density, but not species richness, declined significantly with herbivory of seedlings, regardless of forest size or plot location. Seedling community composition and richness did not differ significantly between the edge and interior of forests across the range of forest sizes (i.e. no edge-effect). Community composition was nested with small forests retaining a subset of the seedling flora of larger forests. Overall, cumulative seedling species richness increased with forest area (i.e. area-effect). Conclusions: Holocene climatic extinction filtering events and area-dependent species relaxation have potentially selected for tree species with convergent life histories adapted to local fragmentation-effects. Stable environmental conditions at old edges in these naturally fragmented forests cause similar regeneration conditions and seedling species composition between edge and interior. Consequently, seedling density and species richness are controlled more by response to gradients of local disturbance (habitat area, herb cover, herbivory) than by proximity to the edge. Large patches (> 50 ha) with intact edges had the highest tree seedling diversity and are a conservation priority. Although small patches contain no unique species they preserve landscape processes, have conservation value, and require protection. Conservation principles derived from recently created Amazonian fragments and that emphasize edge-effects, require critical evaluation for application to old Afromontane patches. Nomenclature: Arnold & de Wet (1993).

Urbanization is an expanding process worldwide, causing major threats to biodiversity through both species extinction and biotic homogenization. Most studies focusing on urban ecosystems have been conducted in temperate forests of the Northern hemisphere; the ecological and socioeconomic contexts, however, may influence biodiversity responses to urbanization. We ask whether the biomes (here, the humid subtropical forest and the semiarid shrubland) where human settlements and land uses are developed determine bird diversity along urbanization gradients in the southern Neotropics. We propose theoretical responses based on expected variations in vegetation cover along urbanization gradients and fit our data to different models of bird richness from highly developed to non-urban areas and also examine changes in species composition. Species richness was positively correlated to vegetation cover in both human settlements. Results supported some of our predictions. In the city located in the arid biome, the highly developed area supported higher bird richness than the natural habitat, unlike the city from the humid biome; yet, the native bird assemblage was better preserved in the urban area established in the humid biome. Richness in moderately developed areas was either higher than or similar to that in rural or natural areas in the settlement from the arid biome, but lower than or similar to richness in the humid biome. In all the studied urban–rural gradients, bird richness reached a plateau in moderately developed areas, in contrast to urban-natural habitat gradients, where richness either increased (in the humid biome) or declined (in the arid biome). Our study helps to understand how the mechanisms changing biodiversity in urbanized areas may act in different biomes and land uses, and therefore contributes to the search of global explanations of diversity patterns.

Aim Extreme droughts, intensified by climate change, threaten floodplain ecosystems. However, the mechanisms underlying biotic responses remain insufficiently understood. We assessed drought‐induced changes in the taxonomic and functional structure of fish communities, identified key environmental and biotic drivers during the drought period, and evaluated post‐drought community recovery trajectories. Location Poyang Lake, Yangtze River Basin, China. Methods Fish assemblages were surveyed across four floodplain lakes of Poyang Lake from 2022 to 2024 during the same seasonal window to isolate drought effects. Community composition and traits were analysed in multivariate trait space to assess changes in functional identity and the abundance of key species, and diversity indices at multiple scales were calculated. Key environmental drivers were identified using ordination and trait‐environment association analyses. Results Extreme drought induced substantial shifts in fish community structure and functional composition, favouring small‐bodied, benthopelagic omnivores and causing a 94% decline in the abundance of the apex predator Culter alburnus. Simultaneously, taxonomic and functional α‐diversity declined significantly, while β‐diversity increased, driven primarily by species turnover. The mechanisms underlying community assembly also shifted, with physicochemical factors predominant before the drought, but macrophyte growth form and macrobenthic biomass becoming the dominant drivers during drought conditions. Although hydrological connectivity was restored in 2024, community recovery remained incomplete, characterised by only partial functional trait rebound and persistent suppression of taxonomic richness, particularly among habitat specialists. Main Conclusions Extreme drought functioned as a basin‐scale filter, selectively favouring fish assemblages with drought‐tolerant trait combinations while leading to the decline or local extinction of intolerant taxa. The resulting habitat contraction and fragmentation reduced the local capacity to support biodiversity and promoted niche partitioning along gradients of habitat structure and food availability. Even after the restoration of hydrological connectivity, drought‐induced habitat legacies and priority effects constrained specialist recovery, impeding the re‐establishment of pre‐drought community composition.

Aim: Large-scale biodiversity patterns are often discussed in the context of 'out of the tropics' (OTT) dynamics and/or tropical niche conservatism (TNC), but empirical evidence of these processes remains very limited. The aim of this study was to infer diversification processes and mechanisms of Cenozoic diversity dynamics using woody angiosperms. Location: East Asian continental islands and global. Time period: Cenozoic. Major taxa studied: Woody plants. Methods: We compiled Cenozoic fossil and modern records for woody angiosperm genera to reconstruct biodiversity patterns. To evaluate the relative importance of TNC and OTT, we investigated extinction/survival patterns and latitudinal range dynamics for each genus, in combination with their clade age (mean family age), cold tolerance and per-genus species richness. Results: We found diversity decreasing with latitude in modern-day flora, but not in the warmer periods of the Neogene and Palaeogene. The percentage of genera surviving decreased with latitude through the Cenozoic. Older genera with less cold tolerance and/or species-poor genera went extinct locally at high latitudes in response to post-Pliocene global cooling. Evolutionarily younger temperate genera dispersed from the extratropics to lower latitudes and the Southern Hemisphere after the Neogene. Main conclusions: The latitudinal diversity gradient (LDG) has rapidly steepened post-Pliocene through: (a) selective extinction in higher latitudes of old, less-diversified tropical genera with low freezing tolerance, and (b) equatorward distributional shift of temperate genera. Both these processes were driven by the high-latitude cooling. Such major roles of TNC and OTT, wherein temperate genera in the Northern Hemisphere expanded through the tropics into higher latitudes of the Southern Hemisphere across climatic boundaries without losing their temperate presence, are in contrast to OTT processes in marine systems. Cenozoic patterns of terrestrial woody angiosperm biodiversity indicate the importance of TNC and high-latitude processes, including the extinction of tropical genera and range contraction or shift of temperate genera.

The relative importance of environmental colour for extinction risk compared with other aspects of environmental noise (mean and interannual variability) is poorly understood. Such knowledge is currently relevant, as climate change can cause the mean, variability and temporal autocorrelation of environmental variables to change. Here, we predict that the extinction risk of a shorebird population increases with the colour of a key environmental variable: winter temperature. However, the effect is weak compared with the impact of changes in the mean and interannual variability of temperature. Extinction risk was largely insensitive to noise colour, because demographic rates are poor in tracking the colour of the environment. We show that three mechanisms—which probably act in many species—can cause poor environmental tracking: (i) demographic rates that depend nonlinearly on environmental variables filter the noise colour, (ii) demographic rates typically depend on several environmental signals that do not change colour synchronously, and (iii) demographic stochasticity whitens the colour of demographic rates at low population size. We argue that the common practice of assuming perfect environmental tracking may result in overemphasizing the importance of noise colour for extinction risk. Consequently, ignoring environmental autocorrelation in population viability analysis could be less problematic than generally thought.