Among the local processes that determine species diversity in ecological communities, fluctuation‐dependent mechanisms that are mediated by temporal variability in the abundances of species ...populations have received significant attention. Higher temporal variability in the abundances of species populations can increase the strength of temporal niche partitioning but can also increase the risk of species extinctions, such that the net effect on species coexistence is not clear. We quantified this temporal population variability for tree species in 21 large forest plots and found much greater variability for higher latitude plots with fewer tree species. A fitted mechanistic model showed that among the forest plots, the net effect of temporal population variability on tree species coexistence was usually negative, but sometimes positive or negligible. Therefore, our results suggest that temporal variability in the abundances of species populations has no clear negative or positive contribution to the latitudinal gradient in tree species richness.
We quantified temporal population variability for tree species in 21 large forest plots and found much greater variability for higher latitude plots with fewer tree species. In addition, we used a fitted mechanistic model to show that among the forest plots, the net effect of temporal population variability on tree species coexistence was usually negative, but sometimes positive or negligible. Therefore, our results suggest that temporal population variability has no clear negative or positive contribution to the latitudinal gradient in tree species richness.
Little is known on the effects of degradation and disturbance on bird assemblage in lowland karst forests in the Philippines. In this study, we determined diversity patterns and distribution of birds ...along the vertical strata in two karst forest fragments adjacent to and one reforestation area within an active limestone quarry area in Bulacan province, Luzon island. Surveys were conducted using mist nets set in the understory (0–3 m) and sub-canopy (4–10 m) from November 2013 to October 2016. A total of 617 individuals belonging to 63 species and 13 feeding guilds were recorded from a mist-netting effort of 654,264.8 mist-net hours (m2∙h); of these, 32 are Philippine endemics and six are threatened species. We recorded the highest number of species in the reforestation area, most of which are generalist and disturbance-tolerant species. Results from permutational multivariate analysis of variance (PERMANOVA) and non-metric multidimensional scaling (NMDS) indicate differences in bird assemblage between the three habitat types and between the two vertical strata within habitat types. Meanwhile, similarity percentage analyses and Mann-Whitney U tests showed that species and guilds that contributed to the observed dissimilarity in the two strata have higher capture rates in the understory. These observations provide insights into the effect of disturbance and habitat alteration in the vertical movement of birds, as evidenced by the shift of some arboreal species to the understory layer in more disturbed habitats. Understanding the behavior and habitat use of birds will, thus, help in identifying appropriate conservation measures to ensure proper resource partitioning among the different bird assemblages in fragmented habitats.
Urban environments are not considered areas with conservation importance. However greenspaces in cities have been previously identified as areas with significant avian biodiversity. We investigated ...the distribution and diversity of birds in what are increasingly considered as Metropolitan Manila's last greenspaces; the University of the Philippines campus, military cemeteries and two government operated parks. Using species–area analysis, abundance and diversity indices, TWINSPAN ordination and logistic regression to determine important landscape features for species presence, we describe the distribution of bird communities and diversity in Metropolitan Manila. Two major bird community groupings were observed. These are the urban exploiters and the urban adaptable with the former occurring in high abundances and the latter in low abundances in greenspaces. The number of built and natural spatial entities determines abundances. Species area analysis suggests that the greenspaces are distinct habitats that preserve faunal uniqueness whereas urbanization tends to decrease diversity. These observations suggest that greenspaces harbor significant avian biodiversity as well as the presence of endemic and threatened species. As the greenspaces possess remnant wetland and wooded habitat we recommend that they be preserved and maintained by ensuring that these habitats are incorporated in any urban development plan.
The diversification in call features across different echolocating bat species can provide sufficient information for reliable species identification. In the Philippines, bat bioacoustics is still a ...growing field. There is a need for a well-developed reference library of calls from different species of insectivorous bats, representing different habitats across each species’ geographic ranges. This study aims to contribute to the building of an echolocation call library for Philippine insectivorous bats. We describe the echolocation calls of 15 species from five families captured in Bulacan province on the island of Luzon. A total of 321 echolocation calls from 105 individuals released in an enclosure were recorded using a Pettersson Elektronik M500 USB ultrasound microphone. Using discriminant function analysis, we assessed the potential of using call parameters in classifying bat echolocation calls to species correctly. Regardless of sample size, correct overall cross-validated classification levels were 92.8% for CF-dominated calls from Hipposideridae and Rhinolophidae families, and 96.9% for FM-dominated calls from Vespertilionidae and Miniopteridae families. When variations in classification levels due to sample size were considered, 98.4% of CF-component dominated calls (four species removed due to small sample size) and 98.9% of FM-component dominated calls (one species removed due to small sample size) were successfully classified into their species. Calls from one species under the Emballonuridae family were characterized. We found some conflicts in identification between species belonging to species complexes, particularly within Hipposideridae. Nevertheless, our results have shown that echolocation calls can be a reliable method in the identification of insectivorous bat species and can complement morphometric and molecular data. The current research contributes to the bat call library we are building as a reference for future taxonomic and ecological studies in the Philippines.
Population genetics has been widely employed in conservation studies to assess genetic diversity, gene flow, and population structure. This information can be used to understand the population’s ...fitness. The Philippine dawn bat Eonycteris robusta is a nectarivorous fruit bat that is ecologically important because of its capability to pollinate trees. It is categorized as “Vulnerable” in the Philippine Red List and the IUCN (International Union on the Conservation of Nature) Red List. Fragmentation and loss of forest habitats along with biogeographical factors might impact gene flow and affect the genetic diversity of this species. Thus, a population genetic study was done to assess gene flow and population structure of this species from two sites in the island of Luzon: Palanan, Isabela and Puning Cave, Doña Remedios Trinidad, Bulacan. Ten (10) microsatellite markers were developed from the whole genome of E. robusta and these were used for genotyping individuals. Observed heterozygosity (Ho) was generally lower than the expected (He), suggesting loss of heterozygosity. The inbreeding coefficient values (F) across all loci were greater than 0.5, which meant that mating between closely related individuals was frequent. A low level of gene flow was detected between Palanan and Puning Cave with the presence of structuring (Fst = 0.190 ± 0.003; Nm = 1.068 ± 0.020). Deviations from the Hardy-Weinberg equilibrium (HWE) were also observed for most of the loci tested. Clustering was also evident in the principal coordinates analysis (PCoA) plots, showing a distinct cluster of Puning Cave samples separate from Palanan, Isabela. This study has shown that within island clustering is possible, which may be driven by ecological factors such as discontinuity of available habitats for E. robusta or by biogeographical features like distance and topography
A new species,
Medinillatheresae
Fernando, from ultramafic soils on Dinagat and Mindanao Islands, Philippines is described and illustrated. The species is characterized by its terrestrial erect ...habit, non-setose nodes, 3-plinerved, lanceolate and coriaceous leaves arranged in whorls, cauline or axillary and pendulous inflorescences, rounded flower buds, 4-merous flowers, and straight anthers. It is compared with other similar species in the
Medinillapendula
Merr. complex.
This study represents the first molecular survey of the ichthyofauna of Taal Lake and the first DNA barcoding attempt in Philippine fishes. Taal Lake, the third largest lake in the Philippines, is ...considered a very important fisheries resource and is home to the world’s only freshwater sardine, Sardinella tawilis. However, overexploitation and introduction of exotic fishes have caused a massive decline in the diversity of native species as well as in overall productivity of the lake. In this study, 118 individuals of 23 native, endemic and introduced fishes of Taal Lake were barcoded using the partial DNA sequence of the mitochondrial cytochrome c oxidase subunit I (COI) gene. These species belong to 21 genera, 17 families and 9 orders. Divergence of sequences within and between species was determined using Kimura 2‐parameter (K2P) distance model, and a neighbour‐joining tree was generated with 1000 bootstrap replications using the K2P model. All COI sequences for each of the 23 species were clearly discriminated among genera. The average within species, within genus, within family and within order percent genetic divergence was 0.60%, 11.07%, 17.67% and 24.08%, respectively. Our results provide evidence that COI DNA barcodes are effective for the rapid and accurate identification of fishes and for identifying certain species that need further taxonomic investigation.
Survival rates of large trees determine forest biomass dynamics. Survival rates of small trees have been linked to mechanisms that maintain biodiversity across tropical forests. How species survival ...rates change with size offers insight into the links between biodiversity and ecosystem function across tropical forests. We tested patterns of size-dependent tree survival across the tropics using data from 1,781 species and over 2 million individuals to assess whether tropical forests can be characterized by size-dependent life-history survival strategies. We found that species were classifiable into four 'survival modes' that explain life-history variation that shapes carbon cycling and the relative abundance within forests. Frequently collected functional traits, such as wood density, leaf mass per area and seed mass, were not generally predictive of the survival modes of species. Mean annual temperature and cumulative water deficit predicted the proportion of biomass of survival modes, indicating important links between evolutionary strategies, climate and carbon cycling. The application of survival modes in demographic simulations predicted biomass change across forest sites. Our results reveal globally identifiable size-dependent survival strategies that differ across diverse systems in a consistent way. The abundance of survival modes and interaction with climate ultimately determine forest structure, carbon storage in biomass and future forest trajectories.
Treeshrews are small, squirrel-like mammals in the order Scandentia, which is nested together with Primates and Dermoptera in the superordinal group Euarchonta. They are often described as living ...fossils, and researchers have long turned to treeshrews as a model or ecological analogue for ancestral primates. A comparative study of colour vision-encoding genes within Scandentia found a derived amino acid substitution in the long-wavelength sensitive opsin gene (
) of the Bornean smooth-tailed treeshrew (
). The opsin, by inference, is red-shifted by
6 nm with an inferred peak sensitivity of 561 nm. It is tempting to view this trait as a novel visual adaptation; however, the genetic and functional diversity of visual pigments in treeshrews is unresolved outside of Borneo. Here, we report gene sequences from the northern smooth-tailed treeshrew (
) and the Mindanao treeshrew (
, the senior synonym of
). We found that the opsin genes are under purifying selection and that
shares the same substitution as its congener, a result that distinguishes
from other treeshrews, including
We discuss the implications of opsin functional variation in light of limited knowledge about the visual ecology of smooth-tailed treeshrews.
The Philippines is both a megadiversity country and a global biodiversity hotspot. The diversity patterns of three major plant groups were assessed: (1) trees (trees and palms), (2) herbs (grasses, ...shrubs, forbs, ferns), and (3) epiphytes (climbers and epiphytes), by determining the changes in compositional and species richness patterns in two forest conditions, i.e., remnant forests and exotic tree species-based reforested areas, in active forest over limestone quarries in the Luzon and Mindanao biogeographic sub-regions of the Philippines. We identified 458 species comprising 266 tree species, 95 herbaceous species and 97 epiphyte species. Of these, 21 species were categorized as threatened species. Species composition differed between remnant forests and exotic tree species-based reforested areas for tree species and epiphyte species, while composition differences between the Luzon and Mindanao biogeographic sub-regions were limited to tree species only. Differences in species diversity (in terms of richness) were observed between biogeographic sub-regions for all plant groups, while differences between forest conditions were found for tree and epiphyte species only. Interestingly, there were significantly fewer numbers of exotic species in bigger remnant forest sites and in older exotic tree species-based reforested sites, while larger numbers of native species occurred in older than in younger exotic tree species-based reforested sites. The results emphasize the importance of understanding forest recovery in disturbed ecosystems. Conservation attention should focus on protecting remaining forests and planting native species as part of a forest restoration strategy to enhance faster forest recovery and re-connecting remnant forest patches.
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