Ecological differences of south polar skua populations from Fildes Peninsula of King George Island and eastern Larsemann Hills, Antarctica

A study has been done on the comparison of nesting and feeding behavior, population variances as well as breeding success between two populations of south polar skua (Catharacta maccormicki) from near Great Wall station on Fildes Peninsula and near Zhongshan station in Eastern Larsemann Hills, Antarctica. There are evident differences in their population ecology. The foraging habit is much related to regional ecosystem and food resources near their territorial area. Dependence on human food waste influences skua's diet,which considerably affects their behavior even population variation in both areas. The skuas in Zhongshan Station,could shorten and/or regulate the timing for their egg laying and hatching, and take precedence of one chick brooding, for keeping their breeding success, and subsequent species continuation.

Damage characteristics of three boring pests in Artemisia ordosica

The population density and distribution of the three major boring pests, Holcocerus artemisiae, Sphenoptera sp. and Adosopius sp. were studied in their host plant Artemisia ordosica. Results show that the larvae ofH. artemisiae mainly bore the rhizome ofA. ordosica, but also the larvae of Sphenoptera sp. and Adosopius sp. bore the rhizome of A. ordosica. The adults of Sphenoptera sp. and Adosopius sp. feed on the leaves of A. ordosica as a nutritional supplement. The distribution of the larvae of three pests in their host plant is completely different. H. artemisiae and Sphenoptera sp. are distributed in the whole A. ordosica plant. The newly hatched larvae first feed on the phloem and xylem of stem and then burrow to the roots before the winter of the same year. However, ,4dosopius sp. is distributed mainly in the roots. The newly hatched larvae move from the phloem to the xylem, and gradually damage the lower part of the trunk. The larvae of the three pests sometimes coexist in a single A. ordosica plant. However, the probability of the coexistence of the three pests is very small. The highest probability of coexistence of two pests was observed in Sphenoptera sp. and H. artemisiae, while the probability of coexistence of Sphenoptera sp. and Adosopius sp. as well as H. artemisiae and Adosopius sp. was smaller. The reasons for coexistence or its avoidance are not only related to the amount of food provided nor the volume of larval living space in a single A. ordosica plant, but also related to the development characteristics of different kinds of larvae and interspecific competition.

Microgeographic Variation and Inter-Riffle Migration of <i>Rhinichthys atratulus</i>(Pisces: Cyprinidae) in a Small Connecticut Stream, United States

We examined the genetic diversity on a microgeographic scale of Rhinichthys atratulus (Eastern Blacknose Dace) in Allyn Brook, a small tributary in the upper Coginchaug River drainage in Connecticut. By looking at gene flow on a microgeographic scale among populations that had no physical barriers to migration, we tested the null hypothesis that the populations should be homogeneous. We resolved seven polymorphic microsatellite loci and one mitochondrial gene, nd2, in three adjacent populations (<0.5 km) in Allyn Brook and compared these populations to the two closest populations (>5 km) in the Coginchaug River. A dam from the 1920’s in lower Allyn Brook has isolated Allyn-Brook populations from Coginchaug-River populations. Allyn Brook was selected because there are only three riffle habitats in the brook and, therefore, there can be no immigration from upstream populations. Each population has private (i.e., unique) alleles and haplotypes, and there are significant genetic differences between all sites. The Allyn Brook populations are almost as different from one another as they are from the distant populations in the Coginchaug River from which they have been isolated for more than 80 years. These results point to in situ evolution and little migration or gene flow among populations on a microgeographic scale. This raises interesting questions for conservation of genetic diversity of stream fishes.

Variation in abundance and habitat relationship of three understory insectivorous birds in a disturbed landscape of Neotropical dry forest of Colombia

Background:Evaluating relationships between avian populations and their habitat is important for understanding the biology of these species and for management decisions that improve the effectiveness of restoration practices.We investigated how habitat variation along a disturbance gradient affected the abundance of three insectivorous bird species,White-bellied Antbird(Myrmeciza longipes),Barred Antshrike(Thamnophilus doliatus),and Pale-breasted Spinetail(Synallaxis albescens)in a Neotropical dry forest remnant in central Colombia.Methods:The study area,which is located in Magdalena Valley,is under ecological restoration after the construction of the“El Quimbo”hydroelectric dam,with a gradient of habitat conditions,from relatively advanced secondary growth to recently disturbed areas.We conducted bird surveys and quantified the habitat conditions from June 2018 to June 2019.We compared the relative abundance of the birds among the three zones with increasing disturbance and modeled the relationship between the bird abundance with the micro-and landscape-habitat conditions,with Poisson generalized linear model regression.Results:The relative abundance of the three bird species varied according to the habitat features and disturbance level.The abundance of White-bellied Antbirds was higher in forests and thickets than shrubland fragments;Barred Antshrike was more abundant in shrubland and thickets than in forest fragments,and Pale-breasted Spinetail had the highest abundance in shrubland and the lowest in forest fragments.The abundance of both White-bellied Antbird and Pale-breasted Spinetail did not differ among zones with different levels of disturbance,while the abundance of Barred Antshrike decreased in zones with more disturbance.Conclusions:There were significant differences in the habitat relationships of the three understory insectivorous species along the disturbance gradient,although these species were within the same trophic group.These bird species preferred different stages of habitat succession and responded to different habitat and landscape features.Increasing forest fragment areas and decreasing the amount of edge would be useful restoration priorities for these and other similar avian species in this study area.

It is time to mate: population-level plasticity of wild boar reproductive timing and synchrony in a changing environment

On a population level,individual plasticity in reproductive phenology can provoke either anticipations or delays in the average reproductive timing in response to environmental changes.However,a rigid reliance on photoperiodism can constraint such plastic responses in populations inhabiting temperate latitudes.The regulation of breeding season length may represent a further tool for populations facing changing environments.Nonetheless,this skill was reported only for equatorial,nonphotoperiodic populations.Our goal was to evaluate whether species living in temperate regions and relying on photoperiodism to trigger their reproduction may also be able to regulate breeding season length.During 10 years,we collected 2,500 female reproductive traits of a mammal model species(wild boar Sus scrofa)and applied a novel analytical approach to reproductive patterns in order to observe population-level variations of reproductive timing and synchrony under different weather and resources availability conditions.Under favorable conditions,breeding seasons were anticipated and population synchrony increased(i.e.,shorter breeding seasons).Conversely,poor conditions induced delayed and less synchronous(i.e.,longer)breeding seasons.The potential to regulate breeding season length depending on environmental conditions may entail a high resilience of the population reproductive patterns against environmental changes,as highlighted by the fact that almost all mature females were reproductive every year.

Abiotic drivers shape seed inputs and outputs in a tropical wetland on Croton trinitatis population

Background:Predicting how natural and anthropogenic drivers shape different ecological indicators,such as plant populations along environmental gradients,can be a relevant tool for establishing management and conservation criteria of tropical wetlands.We aimed to assess the effects of seasonal flood disturbance,type of grasslands and topographical conditions on Croton trinitatis population distribution in a tropical wetland.Methods:The study was carried out in a seasonally flooded grassland(Central-West Brazil).We conducted samplings of soil on the dry and flood hydrophases of the Pantanal.We took the samples in eight seasonal ponds,with 1 km interval between them.Transects were marked during the flood period,observing the water level,one in the lowest zone,in the middle of the pond=low(ca.60 cm deep),one at the pond edge=mid(ca.30 cm deep)and one in the higher zone,on the external part=high(ca.1 cm deep).Results:The results showed that the topography,seasonality,and types of grassland determine differences in the abundance patterns of adult plants and seedlings,and seed bank and seed predation.The abiotic factors can shape plant population-related ecological processes and patterns,with outputs(germination and predation)and inputs(local dispersion and from neighbouring areas)of proportional seeds for the population maintenance in this environment.Conclusion:We emphasize the importance of these findings,to show that abiotic factors are not the only ones to be considered in ecological studies of distribution and structuring of populations in habitats with extreme seasonal events.