Comparative population genomics reveals glacial cycles to drive diversifications in tropical montane birds(Aves,Timaliidae)

Many bird species are specialized to live in the broadleaved,evergreen forests in the mountain regions in Southeast Asia.These mountain habitats are not continuously distributed as the different mountain areas are separated by lowlands,which has restricted gene flow and thus contributed to the high biological diversity in this region.The degree of connectivity between mountain areas has fluctuated with the Pleistocene glacial cycles,being largest during the glaciations when the mountain forests spread to lower elevations.Here we study how the intermittent periods of restricted gene flow and connectivity between the populations of five montane species of babblers(Aves,Timaliidae)in Vietnam may be traced in their genomes.The results suggest that the babbler species in the Central Highlands have been isolated from their sister-populations in northern Vietnam for between ca.585 and 380 ky.For two species with populations in both the Central Highlands and the Da Lat region,we found that these split at more or less the same time(440–340 kya).We also found a significant statistical correlation between the time of the splits of these populations and the lowest altitude at which they are known to occur(no similar correlation was found with the geographic distances between populations).The populations in northern Vietnam show higher genetic variation than their counterparts in South-Central Vietnam,supporting the postulate that smaller populations may have lower genetic variation than larger.In accordance with this,we found the lowest genetic variation in the two species with the smallest populations in the Central Highlands.These two populations also show low levels of genomic heterozygosity.Our results show that the south-central populations of the studied babbler species are genetically distinct from their sister-populations in northern Vietnam,providing additional argument for the long-term protection of the evergreen mountain forests in Southeast Asia.

Habitat partitioning by two sympatric Turdoides species in the vicinity of lake Naivasha,Kenya

Two species of babblers, Black-lored Babbler (Turdoides sharpie) and Arrow-marked Babbler (Turdoides jardeneii) are sympatric around lakes Naivasha and Nakuru, Kenya. This study was carried out to assess the habitat partitioning mechanisms of the two species around Lake Naivasha area. The charactretistics of habitats used by seven groups of each species were studied along the shorelines of lakes Naivasha and Oloiden. The two species differed significantly in the habitat characteristics. Arrow-marked Babbler is restricted to shorelines with dense tree and ground vegetation cover while Black-lored Babbler occupies open areas with sparsely distributed small trees and short ground vegetation cover. Observations on the feeding habits and social behaviours of the two species are also discussed.

Novel insights into the historical biogeography of the streak-breasted scimitar babbler complex （Aves： Timaliidae： Pomatorhinus ruficollis complex）

The Streak-breasted Scimitar Babblers of the Pomatorhinus ruficollis species complex are found in most of the forested habitats across southern and eastern Asia. The diversification history of this group is obscured by high plumage variation across populations and conflicting genetic signal across loci. We combined genetic and geographic data from several recent studies to investigate how these species diversified across China using both phylogenetic and ecological niche modeling analyses. These two lines of evidence are consistent in showing that two well-sampled species, P. reconditus and P. nigrostellatus, in central and southern China respectively, likely experienced a history of isolation and expansion as suitable habitat contracted during the last interglacial and expanded in patchy extent during the glacial maximum. The genetic analysis showed that populations of P. nigrostellatus on Hainan Island are very similar to the ones in nearby mainland southern China. We recovered two well-supported clades within P. reconditus that were not geographically structured with both containing individuals from the same localities across central China. This phylogenetic result corresponded to the ecological niche models that showed expansion from refugia since the last interglacial. This study illustrates the value of using an integrative approach and detailed geographic sampling to help understand the recent diversification of birds in China [Current Zoology 61 （5）： 910-921, 2015].

Bird community comparisons of four plantations and conservation concerns in South China

Plantations of non-native,fast-growing trees are increasing in the tropics and subtropics,perhaps with negative consequences for the native avifauna.We studied bird diversity in 4 types of plantations in South China to deter-mine which plantation types are especially detrimental,and compared our findings with studies in nearby natu-ral forests to assess the magnitude of the negative impact.A total of 57 species was recorded.The mean capture rate of understory birds was 1.7 individuals 100-net-h-1.Bird richness and capture rate were lower in plantations than in nearby natural forests.Babblers(Timaliidae),primarily forest-dependent species in South China,were particularly under-represented in plantations.Species richness,composition and bird density,particularly of un-derstory birds,differed between plantation types.Plantations of Schima,which is native to South China,had the highest species richness according to point count data.Plantations of Acacia(non-native)supported the highest understory species richness and produced the highest capture rate of understory birds,probably because of their complex structure and high arthropod abundance.If bird diversity is to be considered,we strongly recommend that future re-afforestation projects in South China should,as far as possible,use mixed native tree species,and especially Schima,ahead of the other species.