CONTEMPORARY CULTURAL EVOLUTION OF A CONSPECIFIC RECOGNITION SIGNAL FOLLOWING SERIAL TRANSLOCATIONS

The divergence of conspecific recognition signals (CRS) among isolated populations facilitates the evolution of behavioral barriers to gene flow. The influence of CRS evolution on signal effectiveness in isolated populations can be assessed by testing the salience of changes in CRS from surviving ancestral populations but founder events are rarely detected. The population history of the North Island (NI) saddleback Philesturnus rufusater is absolutely known following conservation translocations which increased the number of populations from 1 to 15. With one exception there is no gene flow between these populations. The translocations have generated interisland divergence of male rhythmical song (MRS), a culturally transmitted CRS. We conducted an experimental test of behavioral discrimination in NI saddlebacks exposed to familiar and unfamiliar MRS and found that responses were significantly stronger for familiar MRS, consistent with a model of contemporary cultural evolution leading to discrimination between geographic song variants. Significantly, this result demonstrates the rapid tempo with which discrimination of CRS might evolve within isolated populations and supports both bottleneck and cultural mutation hypotheses in CRS evolution. The evolutionary implications of contemporary cultural evolution in the production and perception of CRS merit debate on the time frames over which conservation management is evaluated.     

广州市珍稀濒危植物资源状况及保护策略

目前调查到广州市有20种国家重点保护植物和5种广东省重点保护植物。在野外调查的基础上,根据植物居群的大小和数量以及受威胁等级,建议将广州市分布的14种野生植物列为市级重点保护对象。通过分析植物的生存现状和受威胁因素等,对广州市野生珍稀濒危植物的保护提出了相应对策。     

Riparian Conservation Facilitated Expansion of Gray Hawks

Desert riparian ecosystems are among the most threatened biodiversity hotspots in the United States, and efforts to conserve them have been increasing. In 2010–2011 and 2014–2016, we examined shifts in the distribution, habitat characteristics, diet, nest success, and productivity of the gray hawk (Buteo plagiatus), 25 years after a Riparian National Conservation Area was established along the San Pedro River in Arizona, USA, to determine how the removal of grazing and agriculture may have affected the ecosystem. The gray hawk population increased and expanded from mesquite (Prosopis spp.)-dominated areas that they historically occupied into areas that were dominated by grassland. In contrast with the 1990s, percent of mesquite cover in pairs' territories did not correlate with their productivity. Gray hawk diets also included more mammals in our study period, particularly in territories with more grassland. We propose that conservation measures created habitat for gray hawks in areas that were previously unsuitable by allowing grasslands to regenerate and become habitat for their prey, and that management strategies in the San Pedro Riparian National Conservation Area could serve as a model for conservation of other desert riparian ecosystems. © 2020 The Wildlife Society.     

Seasonal development of apothecia of the cereal eyespot pathogen Tapesia yallundae on straw stubble in the UK

Five field sites growing winter wheat were inoculated with isolates of the W-and R-types of Tapesia yallundae in 1990 and 1991. After harvest, plots of uncultivated stubble were monitored for the production of apothecia during 1992 and 1993. Apothecia were found on the stem bases of straw stubble over a 9-month period from mid-October to July, but with a peak in numbers present during late January to March, 5 to 7 months after harvest. This was associated with mean monthly temperatures between 3°C and 8°C. Rainfall appeared to be less important than temperature in apothecial development. Single ascospore isolates obtained from apothecia collected from areas inoculated with W-, R-, or mixed W- and R-type isolates all produced colonies with morphologies and growth rates characteristic of the W-type. Thus there was no indication that the W- and R-types are sexually compatible.     

Phylogeography of the dark kangaroo mouse, Microdipodops megacephalus: cryptic lineages and dispersal routes in North America's Great Basin

AIM: The rodent genus Microdipodops (kangaroo mice) includes two sand-obligate endemics of the Great Basin Desert: M. megacephalus and M. pallidus. The dark kangaroo mouse, M. megacephalus, is distributed throughout the Great Basin and our principal aims were to formulate phylogenetic hypotheses for this taxon and make phylogeographical comparisons with its congener. LOCATION: The Great Basin Desert of western North America. METHODS: DNA sequence data from three mitochondrial genes were examined from 186 individuals of M. megacephalus, representing 47 general localities. Phylogenetic inference was used to analyse the sequence data. Directional analysis of phylogeographical patterns was used to examine haplotype sharing patterns and recover routes of gene exchange. Haplotype-area curves were constructed to evaluate the relationship between genetic variation and distributional island size for M. megacephalus and M. pallidus. RESULTS: Microdipodops megacephalus is a rare desert rodent (trapping success was 2.67%). Temporal comparison of trapping data shows that kangaroo mice are becoming less abundant in the study area. The distribution has changed slightly since the 1930s but many northern populations now appear to be small, fragmented, or locally extinct. Four principal phylogroups (the Idaho isolate and the western, central and eastern clades) are evident; mean sequence divergence between phylogroups for cytochrome b is c. 8%. Data from haplotype sharing show two trends: a north-south trend and a web-shaped trend. Analyses of haplotype-area curves reveal significant positive relationships. MAIN CONCLUSIONS: The four phylogroups of M. megacephalus appear to represent morphologically cryptic species; in comparison, a companion study revealed two cryptic lineages in M. pallidus. Estimated divergence times of the principal clades of M. megacephalus (c. 2-4 Ma) indicate that these kangaroo mice were Pleistocene invaders into the Great Basin coincident with the formation of sandy habitats. The north-south and web patterns from directional analyses reveal past routes of gene flow and provide evidence for source-sink population regulation. The web pattern was not seen in the companion study of M. pallidus. Significant haplotype-area curves indicate that the distributional islands are now in approximate genetic equilibrium. The patterns described here are potentially useful to conservation biologists and wildlife managers and may serve as a model for other sand-obligate organisms of the Great Basin.     

Wetland classification and inventory: A summary

Regional, national and local wetland classifications have been developed and successfully applied. These have invariably been orientated towards conservation and management goals, and the information used to assess wetland loss or to assign management priorities. Existing national and regional classification systems have not only been useful, but they provide an essential base for developing an international system. At the international level, differences among existing systems in the definition of a wetland and how wetland types are defined assume great importance and need to be resolved. Classification is an essential prerequisite for wetland inventory. A number of international inventories have been undertaken, although these have not generally utilized the available high technology and data storage systems available through remote sensing and geographic information systems. More extensive international inventories will require standardization of techniques for data collection, storage and dissemination. A minimum data set needs to be defined with standards for data accuracy. An international committee under the auspices of an international agency (e.g. IWRB, Ramsar Bureau, IUCN) needs to be established to develop an international classification system and guidelines for carrying out a complete inventory of the world's wetlands.     

Clonality in the Endangered <Emphasis Type="Italic">Ambrosia pumila</Emphasis> (Asteraceae) Inferred from RAPD Markers; Implications for Conservation and Management

Clonal plants have the ability to spread and survive over long periods of time by vegetative growth. For endangered species, the occurrence of clonality can have significant impacts on levels of genetic diversity, population structure, recruitment, and the implementation of appropriate conservation strategies. Here we␣examine clone structure in three populations of Ambrosia pumila (Nutt.) Gray (Asteraceae), a federally endangered clonal species from southern California. Ambrosia pumila is a perennial herbaceous species spreading from a rhizome, and is frequently found in dense patches of several hundred stems in a few square meters. The primary habitat for this species is upper terraces of rivers and drainages in areas that have been heavily impacted by anthropogenic disturbances and changing flood regimes. RAPD markers were employed to document the number and distribution of clones within multiple 0.25 m² plots from each of three populations. Thirty-one multi-locus genotypes were identified from the 201 stems sampled. The spatial distribution of clones was limited with no genotypes shared between plots or populations. Mean clone size was estimated at 9.10 ramets per genet. Genets in most plots were intermingled, conforming to a guerrilla growth form. The maximum genet spread was 0.59 m suggesting that genets can be larger than the sampled 0.25 m² plots. Spatial autocorrelation analysis found a lack of spatial genetic structure at short distances and significant structure at large distances within populations. Due to the occurrence of multiple genets within each population, the limited spread of genets, and a localized genetic structure, conservation activities should focus on the maintenance of multiple populations throughout the species range.     

北美保护性耕作及对中国的意义

由土壤侵蚀、荒漠化及盐碱化导致的耕地地力退化,严重威胁着中国的农业生产和生态环境．为了阻止耕地地力的持续下降和生态环境进一步恶化,土壤管理方式必须由传统的耕作方式转向保护性耕作．纵观20世纪有关治理耕地水土流失的技术方法,没有哪一项技术可与由美国提出并加以完善的保护性耕作相比．美洲的农业实践证明,保护性耕作可以控制土壤侵蚀,减少劳动量,节省时间和能源,改善土壤耕性,增加土壤有机质,改善水和大气质量,增加土壤生物多样性．通过回顾保护性耕作的发展历史和应用现状。强调了该耕作技术在保持水土和改善土壤性状上的价值和采用保护性措施时应该注意的关键问题。如保护性耕作农机具、化学除草和转变观念等,同时总结了农民在采用保护性耕作时应该采取的具体步骤．总之,面对中国耕地土壤水土流失严重和地力持续下降以及生态环境恶化的严酷现实,保护性耕作应该在中国加以推广采用．     

Limited genetic structure and evidence for dispersal among populations of the endangered Florida grasshopper sparrow, Ammodramus savannarum floridanus

The Florida grasshopper sparrow, Ammodramus savannarum floridanus, is a non-migratory, endangered subspecies endemic to the prairie region of south-central Florida. It has experienced significant population declines and is currently restricted to five locations. We found substantial levels of variation in microsatellites and mtDNA control region sequences, estimates of inbreeding genetic effective population sizes that were much larger than the estimated census size, and no evidence of inbreeding within five sampled populations (n = 105). We also found a lack of genetic structure among populations (F _ST = 0.0123 for microsatellites and θ = 0.008 for mtDNA), and evidence for dispersal between populations, with 7.6% of all individuals identified as immigrants to their population of capture. We suggest that the subspecies be managed as a single management unit on a regional scale rather than as multiple management units on a local subpopulation scale. There is still a limited opportunity to preserve much of the present genetic variation in this subspecies, if immediate measures are taken to reverse the current population decline before this variation is reduced by genetic drift.