Social structure and landscape genetics of the endemic New Caledonian ant Leptomyrmex pallens Emery, 1883 (Hymenoptera: Formicidae: Dolichoderinae), in the context of fire-induced rainforest fragmentation

Habitat fragmentation is a major threat to biodiversity, as it can alter ecological processes at various spatial and trophic scales. At the species level, fragmentation leading to the isolation of populations can trigger reductions in genetic diversity, potentially having detrimental effects on population fitness, adaptability and ultimately population persistence. Leptomyrmex pallens is a widespread rainforest ant endemic to New Caledonia but now confined to habitat patches that have been fragmented by anthropogenic fire regimes over the last 200 years. We investigated the social structure of L. pallens in the Aoupinié region (c.a. 4900 ha), and assessed the impacts of habitat fragmentation on its population genetic structure. Allele frequencies at 13 polymorphic microsatellite loci were compared among 411 worker ants from 21 nests distributed across the region. High within-nest relatedness (r = 0.70 ± 0.02), and a single queen found in 38 % of the nests by pedigree analysis indicate that the species is monogynous to weakly polygynous. Estimates of gene flow and genetic structure across the region were subsequently determined using a combined dataset of single workers per nest and of unrelated foraging workers. These estimates coupled with a comprehensive landscape genetic analysis revealed no evidence of significant population structure or habitat effects, suggesting that the Aoupinié region harbours a single panmictic population. In contrast, analyses of mitochondrial DNA sequence data revealed a high degree of genetic structuring, indicating limited maternal gene flow and suggesting that gene flow among nests is driven primarily by winged males. Overall these findings suggest that fire-induced habitat fragmentation has had little impact on the population dynamics of L. pallens. Additional studies of less mobile species should therefore be conducted to gain further insights into fire related disturbances on the unique biodiversity and function of New Caledonian ecosystems.

The rise of ancient China : fragmentation and amalgamation

This book examines the source of Chinese civilization, foundations of traditional Chinese society and early patterns of power transition. It engages readers in a search for a broad understanding of China's traditional culture and the enduring legacies of the past-in-the-present. It questions the conventional view about China's past, be that of a Confucian, a Communist or a Western ethnocentric historiographer. Most theories concerning the history of China postulate a central culture based on the Yellow River valley and radiating out into the vast areas of what we know as China. Informed by the latest archaeological discoveries, the author points out an alternative view on formation and development of Chinese civilization. Exploring the social and political upheavals that characterized the continuous disintegration and annexation in the 1st millennium BC, the author offers a unique account of the process of periodic fragmentation and amalgamation. Though presented for specialists in the field, virtually every page of this book is intelligible to the lay person, opening a window for anyone interested in the subject to look at this ancient culture from a new angle.

Quantifying the potential impacts of increasing agricultural fragmentation on land value

Societal expectations from rural lands have traditionally focused on the production of food and fibre. Yet the perception of rural areas is changing and they are now seen in many instances to be capable of delivering multiple functions or non‐commodity outputs including land conservation and the preservation of biodiversity, contributing to the sustainable management of renewable natural resources and enhancing the socio‐economic viability of many areas . The overall multi‐functionality is constrained or favoured by biophysical and socio‐economic drivers. As these types of drivers vary spatially and temporally, so does the functionality of the landscape and heterogeneous patterns emerge. Associated with multiple functions at a single location are a variety of pressures which can manifest themselves as conflict between interacting land uses. One such conflict in rural zones is that between agricultural use and residential use. Warrnambool City Council (WCC) is a Local Government Area (LGA) in southwest Victoria where the debate surrounding the best use of rural land is currently being debated. In a region where agriculture has historically been the mainstay of the economy there is some resistance to unplanned conversion to residential use. Despite concerns and much strategy being discussed it appears an investigation quantifying the impacts of these conversions is yet to be done. This paper addresses the issue of the allocation of land by using GIS mapping to incorporate economic, social and environmental attributes, and applying a theoretical economic framework for the optimal allocation of land to the comprehensive data set. Marginal values of land for competing purposes are estimated and discussed. The method is relevant for other regions where the rural/residential interface and associated planning decisions are highly topical.

Genes and song : genetic and social connections in fragmented habitat in a woodland bird with limited dispersal

Understanding the processes leading to population declines in fragmented landscapes is essential for successful conservation management. However, isolating the influence of disparate processes, and dispersal in particular, is challenging. The Grey Shrike-thrush, Colluricincla harmonica, is a sedentary woodland-dependent songbird, with learned vocalizations whose incidence in suitable habitat patches falls disproportionally with decline in tree cover in the landscape. Although it has been suggested that gaps in tree cover might act as barriers to its dispersal, the species remains in many remnants of native vegetation in agricultural landscapes, suggesting that it may have responded to habitat removal and fragmentation by maintaining or even increasing dispersal distances. We quantified population connectivity of the Grey Shrike-thrush in a system fragmented over more than 120 years using genetic (microsatellites) and acoustic (song types) data. First, we tested for population genetic and acoustic structure at regional and local scales in search of barriers to dispersal or gene flow and signals of local spatial structuring indicative of restricted dispersal or localized acoustic similarity. Then we tested for effects of habitat loss and fragmentation on genetic and acoustic connectivity by fitting alternative models of mobility (isolation-by-distance [the null model] and reduced and increased movement models) across treeless vs. treed areas. Birds within 5 km of each other had more similar genotypes and song types than those farther away, suggesting that dispersal and song matching are limited in the region. Despite restricted dispersal detected for females (but not males), populations appeared to be connected by gene flow and displayed some cultural (acoustic) connectivity across the region. Fragmentation did not appear to impact greatly the dispersal of the Grey Shrike-thrush: none of the mobility models fit the genetic distances of males, whereas for females, an isolation-by-distance model could not be rejected in favor of the models of reduced or increased movement through treeless gaps. However, dissimilarities of the song types were more consistent with the model of reduced cultural connectivity through treeless areas, suggesting that fragmentation impedes song type sharing in the Grey Shrike-thrush. Our paper demonstrates that habitat fragmentation hinders important population processes in an Australian woodland bird even though its dispersal is not detectably impacted.