The role of time and species identities in spatial patterns of species richness and conservation

Many conservation actions are justified on the basis of managing biodiversity. Biodiversity, in terms of species richness, is largely the product of rare species. This is problematic because the intensity of sampling needed to characterize communities and patterns of rarity or to justify the use of surrogates has biased sampling in favor of space over time. However, environmental fluctuations interacting with community dynamics lead to temporal variations in where and when species occur, potentially affecting conservation planning by generating uncertainty about results of species distribution modeling (including range determinations), selection of surrogates for biodiversity, and the proportion of biodiversity composed of rare species. To have confidence in the evidence base for conservation actions, one must consider whether temporal replication is necessary to produce broad inferences. Using approximately 20 years of macrofaunal data from tidal flats in 2 harbors, we explored variation in the identity of rare, common, restricted range, and widespread species over time and space. Over time, rare taxa were more likely to increase in abundance or occurrence than to remain rare or disappear and to exhibit temporal patterns in their occurrence. Space–time congruency in ranges (i.e., spatially widespread taxa were also temporally widespread) was observed only where samples were collected across an environmental gradient. Fifteen percent of the taxa in both harbors changed over time from having spatially restricted ranges to having widespread ranges. Our findings suggest that rare species can provide stability against environmental change, because the majority of species were not random transients, but that selection of biodiversity surrogates requires temporal validation. Rarity needs to be considered both spatially and temporally, as species that occur randomly over time are likely to play a different role in ecosystem functioning than those exhibiting temporal structure (e.g., seasonality). Moreover, temporal structure offers the opportunity to place management and conservation activities within windows of maximum opportunity.     

Extra-pair paternity in the monogamous alpine marmot (Marmota marmota): the roles of social setting and female mate choice

Extra-pair paternity (EPP) can be influenced by both social setting and female mate choice. If evidence suggests that females try to obtain extra-pair copulations (EPCs) in order to gain genetic benefits when mated to a homozygous and/or to a related male, females may not be able to choose freely among extra-pair mates (EPMs) as the social mate may constrain female access to EPMs. In this study, we investigated, first, how EPP depended on social setting and specifically on the number of subordinate males in the family group in a highly social and monogamous mammal, the alpine marmot. Second, we investigated how EPP depended on female mate choice for genetic benefits measured as male mate-heterozygosity and within-pair relatedness. Our results reveal, first, that EPP depended on the social setting, increasing with the number of subordinate males. Second, EPPs were related to relatedness between mates. Third, EPMs were found to be more heterozygous than within-pair males. Thus, social setting may constrain female choice by limiting opportunities for EPC. However, after accounting for social confounding factors, female choice for genetic benefits may be a mechanism driving EPP in monogamous species.     

环境规制对企业竞争力的影响

除改进环境源效外．环境规恻对本国企业竟争力的影响也是政策恻定的关键影响因素。传统假设认为环境规铆会负面影响企业竞争力。波特假设认为在一定条件下。环境规制通过创新补偿与先动优势可提高企业竟争力。本文在提出问题的基础上，对上逮假设进行了剖析。然后讨论了该领域研究的新动向．即不确定性因素的存在对环境规恻与企业竟争力关采的影响。提出环境规制能否影响企业的竟争力还依赖于企业面临的内外部条件、环境管理动机等多种因素。     

环境规制是否能激发绿色创新?——基于点-线-面三维框架的可视化分析

伴随生态文明建设确立为国家战略,环境规制与绿色创新日益成为学术领域研究的热点,其中最具代表性的波特假说近年来逐渐成为多领域学者们关注的重点问题,并积累了丰硕的研究成果。本文以1995—2018年Web of Science数据库中波特假说领域相关研究的文献为样本,运用可视化分析软件,基于点-线-面三维框架整理了环境规制与绿色创新、竞争力等相关主题的关键文献、历史路径和关键词聚类等内容。首先,在关键词共被引网络分析的基础上探讨波特假说研究中存在的四个热点方向,即学者们热衷于对波特假说的强版本、狭义版本以及弱版本进行检验;学者们对环境政策的研究细分至具体的政策如能源政策;倾向于利用不同类型的环境规制对企业环境创新进行验证;探究环境规制和环境创新成因之间的关系。接着,运用文献共被引关系路径分析发现两种引证关系路径,即实证引证关系路径和理论引证关系路径。最后,通过对高被引文献的共被引关系进行模块化分析,显示出了五个重要热点聚类:环境绩效与财务绩效;环境管制与竞争力;企业环境行为与环境管理;环境管制与产业区位选择;环境管制与生产效率。从而,得出了未来需要加强波特假说研究的五个方向的建议:一是文献研究对象需要扩展比较,理论支撑有待继续挖掘;二是针对企业异质性进行环境政策特性设计,灵活创新政府政策工具;三是企业主动性加强,推动形成企业层面研究新视角;四是关注跨国贸易,强化环境规制对国际碳转移和污染倾销问题研究;五是拓宽研究方法的新视角,多关注政策工具间交互影响。     

Interacting effects of habitat destruction and changing disturbance rates on biodiversity: Who is going to survive?

Changes in disturbance rates due to climate change may increase or decrease diversity, whereas permanent loss of habitat is generally believed to decrease diversity. It is, however, very likely that the effects of disturbances and habitat destruction interact. Understanding such combined effects is essential to predict the response of communities to global changes and in particular which functional types of species are most endangered. Using an individual-based spatially explicit community model, we investigate (1) whether diversity-disturbance curves alter when spatially uncorrelated or autocorrelated habitat destruction is added, and (2) which functional types of species are able to survive under these altered conditions. Model communities consisted of four functional types of species trading off between colonisation ability and competition strength. We found that habitat destruction may alter both height and shape of diversity-disturbance curves: maximum diversity at intermediate disturbance rates may shift to other disturbance rates or even split into two peaks giving rise to bimodal diversity-disturbance relationships with different sub-communities persisting at low and high disturbance rates. Diversity responded differentially depending on how the colonisation-competition trade-off was represented. Our results suggest that, for trade-offs in seed production rate, generally the best coloniser will better withstand the interacting effects of habitat destruction and changing disturbance rates; however, for trade-offs in mean dispersal distances, functional types characterized by intermediate abilities will perform best. We conclude that predictions of the impacts of changing disturbance rates on biodiversity depend on community structure and cannot be made without knowledge of concurrent permanent habitat destruction.     

经济发展与城市蔓延的Logistic曲线假说及其验证——基于华东地区典型城市的考察

经济发展与城市蔓延一直是学者研究的热点,其假说大都建立在发展与保护矛盾不断激化的基础之上,论文基于国内外城市发展轨迹的判断,提出新的研究假说:经济发展与城市蔓延存在Logistic曲线关系,并选择华东地区典型城市进行实证检验。结果表明:第一,国外(区域)经济发展由快速城市化、工业化初级阶段过渡到高级或后工业化阶段进程中,对城市蔓延扩张的依赖程度逐渐减弱;第二,中国1978—2003年间经济发展与城市蔓延增长具有周期性波动特征,2003年以后两者波动出现明显脱钩或分歧;第三,实证结果显示,上海、南京、无锡和徐州的第二三产业GDP在分别达到2.91×10¹¹、1.02×10¹¹、4.43×10¹⁰、9.42×10¹⁰元时,城市蔓延扩张出现拐点,验证了研究假说,其规模上限分别为8.99×10⁴、6.01×10⁴、2.20×10⁴、3.43×10⁴ hm²。研究结论能够为我国城市蔓延治理和公共政策调整提供科学依据和直接参考。     

Fragmentation effects on an endangered species across a gradient from the interior to edge of its range

Understanding how habitat fragmentation affects individual species is complicated by challenges associated with quantifying species-specific habitat and spatial variability in fragmentation effects within a species’ range. We aggregated a 29-year breeding survey data set for the endangered marbled murrelet (Brachyramphus marmoratus) from >42,000 forest sites throughout the Pacific Northwest (Oregon, Washington, and northern California) of the United States. We built a species distribution model (SDM) in which occupied sites were linked with Landsat imagery to quantify murrelet-specific habitat and then used occupancy models to test the hypotheses that fragmentation negatively affects murrelet breeding distribution and that these effects are amplified with distance from the marine foraging habitat toward the edge of the species’ nesting range. Murrelet habitat declined in the Pacific Northwest by 20% since 1988, whereas the proportion of habitat comprising edges increased by 17%, indicating increased fragmentation. Furthermore, fragmentation of murrelet habitat at landscape scales (within 2 km of survey stations) negatively affected occupancy of potential breeding sites, and these effects were amplified near the range edge. On the coast, the odds of occupancy decreased by 37% (95% confidence interval [CI] –54 to 12) for each 10% increase in edge habitat (i.e., fragmentation), but at the range edge (88 km inland) these odds decreased by 99% (95% CI 98 to 99). Conversely, odds of murrelet occupancy increased by 31% (95% CI 14 to 52) for each 10% increase in local edge habitat (within 100 m of survey stations). Avoidance of fragmentation at broad scales but use of locally fragmented habitat with reduced quality may help explain the lack of murrelet population recovery. Further, our results emphasize that fragmentation effects can be nuanced, scale dependent, and geographically variable. Awareness of these nuances is critical for developing landscape-level conservation strategies for species experiencing broad-scale habitat loss and fragmentation.     

Offspring sex ratio variation in the bridled nailtail wallaby, Onychogalea fraenata

The bridled nailtail wallaby is a sexually size dimorphic, promiscuous, solitary macropod. Sex ratios of pouch young were studied at two sites over 3 years, beginning with 14 months of severe drought. Females that were in better condition were more likely to have sons, and condition was dependent on body size. Females at one site were heavier, were consequently in better condition, and produced more sons than females at the other site. Females that declined in condition had more daughters during the most severe part of the drought than females that maintained condition, but endoparasite infection did not affect the pouch young sex ratio. Age also appeared to affect sex ratio adjustment, because weight was strongly influenced by age. Sex ratio bias was not caused by early offspring mortality, but occurred at conception. Mothers did not appear to bias energy expenditure on sons or daughters; males and females did not differ in condition at the end of pouch life. Pouch young sex ratio variation was most consistent with the Trivers-Willard hypothesis, but could also have been influenced by local resource competition, since sons dispersed further than daughters. Offspring condition was related to survival, and was correlated with maternal condition. Received: 14 April 1998 / Accepted after revision: 10 November 1998     

Sex allocation in a monomorphic seabird with a single-egg clutch: test of the environment, mate quality, and female condition hypotheses

Sex allocation theory posits that mothers should preferentially invest in sons when environmental conditions are favorable for breeding, their mates are of high quality, or they are in good body condition. We tested these three hypotheses in rhinoceros auklets (Cerorhinca monocerata), monomorphic seabirds that lay a single-egg clutch, in 2 years that differed in environmental conditions for breeding. Results supported the environment and mate quality hypotheses, but these effects were interactive: offspring sex was independent of paternal traits in the poor year for breeding, while females mated to larger and more ornamented males reared more sons in the better year. Conversely, offspring sex was unrelated to female condition, as indexed by hatching date. We propose that good rearing conditions enable females to rear sons possessing the desirable phenotypic attributes of their mates. Results also supported two critical assumptions of sex allocation theory: (1) dimorphism in offspring condition at independence: daughters fledged with higher baseline levels of corticosterone than sons and (2) differential costs of rearing sons versus daughters: mothers rearing sons when environmental conditions were poor completed parental care in poorer condition than mothers rearing daughters in the same year and mothers rearing either sex when conditions were better. These novel results may help to explain the disparate results of previous studies of avian sex allocation.     

Adult sex ratio affects divorce rate in the monogamous endoparasite Schistosoma mansoni

“Divorce” (mate switching) rate is known to vary largely both between and within socially monogamous species. Although the adult sex ratio can have an important influence on mating patterns, very few studies have investigated the influence of sex ratio on divorce rate in monogamous species, and even less so from an experimental point of view. In addition, most studies on the causes and consequences of divorce have been performed on vertebrate species, whereas data for invertebrate monogamous species remain scarce. Schistosoma mansoni is a monogamous endoparasite with a complex life cycle characterized by asexual reproduction in the intermediate host and sexual reproduction in the definitive host. In the wild, populations of S. mansoni inside their definitive hosts are characterized by a male-biased sex ratio. We studied the influence of experimentally varying the adult sex ratio on divorce rate in S mansoni, using controlled infections of hosts with clonal populations. The more male-biased the sex ratio was, the more the divorce rate increased, whereas no such effect was observed under a female-biased sex ratio. In this study and for the first time, we showed, by handling the sex ratio, that the divorce rate increases in adult male-biased sex ratio conditions in a monogamous species.