Multiple colonizations from Madagascar and converged acquisition of dioecy in the Mascarene Dombeyoideae (Malvaceae) as inferred from chloroplast and nuclear DNA sequence analyses

Background and Aims

In the Mascarenes, a young oceanic archipelago composed of three main islands, the Dombeyoideae (Malvaceae) have diversified extensively with a high endemism rate. With the exception of the genus Trochetia, Mascarene Dombeyoideae are described as dioecious whereas Malagasy and African species are considered to be monocline, species with individuals bearing hermaphrodite/perfect flowers. In this study, the phylogenetic relationships were reconstructed to clarify the taxonomy, understand the phylogeographic pattern of relationships and infer the evolution of the breeding systems for the Mascarenes Dombeyoideae.

Methods

Parsimony and Bayesian analysis of four DNA markers (ITS, rpl16 intron and two intergenic spacers trnQ-rsp16 and psbM-trnD) was used. The molecular matrix comprised 2985 characters and 48 taxa. The Bayesian phylogeny was used to infer phylogeographical hypotheses and the evolution of breeding systems.

Key Results

Parsimony and Bayesian trees produced similar results. The Dombeyoideae from the Mascarenes are polyphyletic and distributed among four clades. Species of Dombeya, Trochetia and Ruizia are nested in the same clade, which implies the paraphyly of Dombeya. Additionally, it is shown that each of the four clades has an independent Malagasy origin. Two adaptive radiation events have occurred within two endemic lineages of the Mascarenes. The polyphyly of the Mascarene Dombeyoideae suggests at least three independent acquisitions of dioecy.

Conclusions

This molecular phylogeny highlights the taxonomic issues within the Dombeyoideae. Indeed, the limits and distinctions of the genera Dombeya, Trochetia and Ruizia should be reconsidered. The close phylogeographic relationships between the flora of the Mascarenes and Madagascar are confirmed. Despite their independent origins and a distinct evolutionary history, each endemic clade has developed a different breeding systems (dioecy) compared with the Malagasy Dombeyoideae. Sex separation appears as an evolutionary convergence and may be the consequence of selective pressures particular to insular environments.     

北洛河流域食蚜蝇科区系分析

依据世界动物地理区划及中国动物地理区划,对北洛河流域的食蚜蝇科昆虫进行区系分析。北洛河流域在动物地理区划上隶属于古北界的华北亚区,该区分布有食蚜蝇科昆虫52种,隶属于2亚科11族29属,其中包括2个中国新纪录种和7个陕西新纪录种。其区系组成特点是：古北界有17种,占总数的32.70%,古北界和东洋界共有种有35种,占总数的67.31%。     

DNA barcoding reveals the temporal community composition of drifting fish eggs in the lower Hongshui River,China

Determining the temporal community composition of fish eggs in particular regions and understanding the reproductive times of regional fish taxa are key aspects of the management and regulation of regional fish stocks. However, it is extremely difficult to accurately identify fish eggs due to the absence of diagnostic morphological characters. We sampled fish eggs in the lower Hongshuihe River (an upper mainstem of the Pearl River) between May and September 2020. We then used DNA barcoding to determine the species composition of the egg pool and to predict the spawning periods of the identified species. A total of 641 eggs and 17 larvae were chosen for molecular identification; 397 eggs and 17 larvae yielded high‐quality barcoding sequences. The high failure rate (~38%) was most likely due to long‐term storage in low concentrations of ethanol prior to molecular analysis. We successfully classified 392 eggs into 10 species and 13 larvae into four species using public databases. Most of the species identified in the egg pool were small and/or benthic, and migratory species were rare. This may partially reflect the adverse effects of hydropower cascade development in this river section. We also found that spawning periods tended to be species‐specific. Our study provides a reference for the conservation and management of regional fishery stocks.     

New fossil mousebird (Aves: Coliiformes) with feather preservation provides insight into the ecological diversity of an Eocene North American avifauna

Coliiformes (mousebirds) are represented by just six extant species. These species, restricted to sub‐Saharan Africa, are all primarily frugivorous and are among the most sedentary of living birds. Previously described fossil Coliiformes preserving feather traces share the short, rounded wing shape of extant mousebirds. Along with osteological evidence, these observations have been proposed to support poor sustained flight capabilities across the stem mousebird lineage. We report a new species of Coliiformes from the early Eocene (51.66 ± 0.09 Ma) Fossil Butte Member of the Green River Formation, represented by one of the comparatively few fossils from these deposits preserving carbonized traces of the wing and tail feathering. Feather traces indicate an elongate, tapering wing shape similar to that of some extant aerial insectivores, and suggestive of a capacity for sustained and agile open‐air flight. Traces of the rectrices reveal the tail accounted for approximately two‐thirds of the total length of the bird, a proportion similar to that in living mousebirds. Phylogenetic analysis places the new species as a stem representative of Coliiformes, demonstrating for the first time that the two major clades of Coliiformes – Sandcoleidae and Colii – co‐occurred at Fossil Lake. Based on the recovered phylogeny, as well as the osteology and feathering of extant and fossil Coliiformes, the wing shape of the new species is interpreted as apomorphic. In addition to documenting unexpected morphological specialization within stem‐lineage Coliiformes, the new species adds yet another taxon to the emerging reconstruction of the diverse Paleogene avifauna from the tightly dated and nearly synchronous fossiliferous deposits of the Fossil Butte Member. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 685–706.     

Molecular and morphometric variation in two sibling species of the genus Praomys (Rodentia: Muridae): implications for biogeography

The rodent genus Praomys is widely distributed in the African tropics. The species are cryptic, rendering the species taxonomy unclear. There are differences of opinion concerning the specific status of Praomys misonnei and Praomys tullbergi, and their geographical distribution. We sequenced the cytochrome b and/or the 16S gene of 221 specimens from 12 countries in order to evaluate the genetic variability within these two species, and to precisely determine their geographical distribution. Morphological and morphometrical analyses on the sequenced specimens were also performed to find criteria useful for the identification of museum specimens. Our results confirm that P. misonnei and P. tullbergi are two valid species that can be separated by molecular data. However, no single discrete morphological character or simple metric measurement can be used to discriminate them. The percentage of misclassified individuals in multivariate discriminant analysis is relatively high (10%). The two species have allopatric distributions: P. tullbergi occurs in West Africa, from eastern Guinea to western Ghana, and P. misonnei is widely distributed from eastern Ghana to western Kenya. Within P. misonnei we identified three or four major geographical clades: a West Central African clade, an East African clade, a Nigerian clade, and a possible West African clade. Within P. misonnei, high geographical morphometrical variability was also identified. The role of both rivers and Pleistocene forest refugia in promoting speciation within the genus Praomys is discussed. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 397–419.     

Chromosome characterization and biogeographic relations among three populations of the driftwood catfish Parauchenipterus galeatus (Linnaeus, 1766) (Siluriformes: Auchenipteridae) in Brazil

The present study employed basic and molecular cytogenetic methods to characterize three populations of Parauchenipterus galeatus from the basins of the Paraná and São Francisco Rivers, and a region of connection between the two basins. Although the diploid number was equal to 58 chromosomes, variations in karyotype formula were detected among the populations. B chromosomes were detected only in the population from the São Francisco River. Heterochromatin was located in the terminal position in almost all the chromosomes and in the pericentromeric position in some acrocentric chromosomes in the three populations. A single nucleolus organizer region was detected by silver nitrate and 18S rDNA‐fluorescent in situ hybridization in the short arm of one subtelocentric pair in the three populations, varying only in the chromosome pair bearing this site. The 5S rDNA sites were located in two submetacentric chromosome pairs in the three populations, varying only in the chromosome pairs bearing these sequences. Classic and molecular chromosome markers, along with the context of the natural history of the formation of hydrographic basins, ecological aspects, and the geographic isolation of populations between hydrographic basins and within the same basin, were important contributions to the discussion on possible biogeographic relations among the populations of Parauchenipterus galeatus. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 648–656.     

Genetic differentiation and distribution routes of the bronze featherback Notopterus notopterus (Osteoglossiformes: Notopteridae) in Indochina

Mitochondrial DNA analysis was used to investigate genetic variation in the bronze featherback fish Notopterus notopterus in Indochina. Five hundred and five fish samples collected from 11 localities were separated into three genetically differentiated intraspecific groups. Chao Phraya River samples formed a distinct group. Mekong River samples were clearly separated into two different groups, namely, middle and lower Mekong groups. The lower Mekong group was closely related to Malay Peninsula group, even though the two groups are separated by a tract of ocean. F‐values (0.82–0.95) also confirmed genetic differentiation of the middle and lower Mekong groups. Although the two Mekong groups inhabit the same river basin, molecular clock calculations indicate they separated approximately 1.2 Mya, suggesting (1) evolutionary divergence before invasion of the Mekong River; (2) differences in migration routes to the river; and/or (3) differences in the timings of invasion. The complexities of historical events cannot be ignored in determinations of factors responsible for the exceptional biodiversity in the Mekong basin. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 575–582.     

Effects of Exploitation on Black Bear Populations at White River National Wildlife Refuge

Abstract: We live-trapped American black bears (Ursus americanus) and sampled DNA from hair at White River National Wildlife Refuge, Arkansas, USA, to estimate annual population size (N), growth (γ), and density. We estimated N and γ with open population models, based on live-trapping data collected from 1998 through 2006, and robust design models for genotyped hair samples collected from 2004 through 2007. Population growth was weakly negative (i.e., 95% CI included 1.0) for males (0.901, 95% CI = 0.645–1.156) and strongly negative (i.e., 95% CI excluded 1.0) for females (0.846, 95% CI = 0.711–0.981), based on live-trapping data, with N from 1999 to 2006 ranging from 94.1 (95% CI = 70.3–137.1) to 45.2 (95% CI = 27.1–109.3), respectively, for males and from 151.4 (95% CI = 127.6–185.8) to 47.1 (95% CI = 24.4–140.4), respectively, for females. Likewise, mean annual γ based on hair-sampling data was weakly negative for males (0.742, 95% CI = 0.043–1.441) and strongly negative for females (0.782, 95% CI = 0.661–0.903), with abundance estimates from 2004 to 2007 ranging from 29.1 (95% CI = 21.2–65.8) to 11.9 (95% CI = 11.0–26.9), respectively, for males and from 54.4 (95% CI = 44.3–77.1) to 27.4 (95% CI =24.9–36.6), respectively, for females. We attribute the decline in the number of females in this isolated population to a decrease in survival caused by a past translocation program and by hunting adjacent to the refuge. We suggest that managers restructure the quota-based harvest limits until these growth rates recover.     

Anti-phase oscillation of Asian monsoons during the Younger Dryas period: Evidence from peat cellulose δC of Hani, Northeast China

Significant changes in the global atmospheric and oceanic circulation system occurred during the Younger Dryas cold period. Several researchers have demonstrated a weakening of intensity of the Indian Ocean Summer Monsoon during that period. However, the exact characteristics of the East Asian Summer Monsoon still remain vague. Here we present a late-glacial precipitation proxy record of the East Asian Summer Monsoon, based on the peat cellulose δ¹³C found in Hani, Northeast China. Both the peat cellulose record and a pollen record from Lake Sihailongwan sediment indicate an abrupt increase in precipitation in the region during the Younger Dryas period. These results support the occurrence of wet conditions in the north and of dry conditions in the south of the Chinese Mainland during that period. By examining the activity of the East Asian Summer Monsoon on an interannual timescale, we propose a theory for the anomalous precipitation distribution that we attribute to the occurrence of an El Niño-like phenomenon in the Equatorial Pacific Ocean during the Younger Dryas. In this case, the intensity of the Western Pacific subtropical high may strengthen, and its position over the western Pacific Ocean may move northward. This could cause an enhancement of the East Asian Summer Monsoon and migration of a monsoonal rainbelt towards the northern region of the Chinese mainland, resulting in a precipitation distribution of wet conditions in the north and dry conditions in the south. Therefore, this anomalous rainfall distribution should be considered to indicate the strengthening of the East Asian Summer Monsoon, in anti-phase with the Indian Ocean Summer monsoon that weakened during the same period. This agrees with the previously revealed anti-phase variations of the two monsoons during the ice-rafted debris cold events of the North Atlantic Ocean. It appears that, in relation to the abrupt temperature drop in the Northern Hemisphere on centennial to millennial time scales, anti-phase variations of the two Asian summer monsoons occurred.