The source–sink paradigm predicts that populations in poorer‐quality habitats (‘sinks') persist due to continued immigration from more‐productive areas (‘sources'). However, this categorisation of ...populations assumes that habitat quality is fixed through time. Globally, we are in an era of wide‐spread habitat degradation, and consequently there is a pressing need to examine dispersal dynamics in relation to local population change. We used an integrated population model to quantify immigration dynamics in a long‐lived colonial seabird, the black‐legged kittiwake Rissa tridactyla, that is classified as globally ‘Vulnerable'. We then used a transient life table response experiment to evaluate the contribution of temporal variation in vital rates, immigration rates and population structure to realised population growth. Finally, we used a simulation analysis to examine the importance of immigration to population dynamics. We show that the contribution of immigration changed as the population declined. This study demonstrates that immigration is unlikely to maintain vulnerable sink populations indefinitely, emphasising the need for temporal analyses of dispersal to identify shifts that may have dramatic consequences for population viability.
Dispersal is a fundamental process governing the ecological and evolutionary dynamics of any given species. Due to inherent challenges associated with measuring dispersal directly, identifying ...proxies for dispersal capacity has long been an active field of research across ecosystems. In marine systems, pelagic larval duration (PLD) has been one of the most widely used indicators of interspecific dispersal potential. The validity of this proxy, however, relies mostly on the assumption of entirely passive dispersal, a notion that has been challenged by findings of strong larval behavioural capabilities. Here, we assessed the effect of larval swimming capacities measured as mean critical swimming speed (U-crit) on emergent species-level properties related to dispersal potential, population genetic structure and global range size, in demersal marine fishes. In a meta-analytic framework, we tested the relative importance of U-crit versus other in trinsic (PLD, egg type, adult body size) and extrinsic (genetic marker type, study scale) predictors of isolation-by-distance slope, global F
ST and range size. U-crit showed stronger relationships with all emergent response variables than PLD and was consistently the most important predictor in multi-model inference. Our findings indicate that larval swimming capacities could serve as a power ful indicator of a species’ long-distance dispersal potential.
Characterizing genetic diversity in Africa is a crucial step for most analyses reconstructing the evolutionary history of anatomically modern humans. However, historic migrations from Eurasia into ...Africa have affected many contemporary populations, confounding inferences. Here, we present a 12.5× coverage ancient genome of an Ethiopian male ("Mota") who lived approximately 4500 years ago. We use this genome to demonstrate that the Eurasian backflow into Africa came from a population closely related to Early Neolithic farmers, who had colonized Europe 4000 years earlier. The extent of this backflow was much greater than previously reported, reaching all the way to Central, West, and Southern Africa, affecting even populations such as Yoruba and Mbuti, previously thought to be relatively unadmixed, who harbor 6 to 7% Eurasian ancestry.
Animal movement impacts the spread of human and wildlife diseases, and there is significant interest in understanding the role of migrations, biological invasions and other wildlife movements in ...spatial infection dynamics. However, the influence of processes acting on infections during transient phases of host movement is poorly understood. We propose a conceptual framework that explicitly considers infection dynamics during transient phases of host movement to better predict infection spread through spatial host networks. Accounting for host transient movement captures key processes that occur while hosts move between locations, which together determine the rate at which hosts spread infections through networks. We review theoretical and empirical studies of host movement and infection spread, highlighting the multiple factors that impact the infection status of hosts. We then outline characteristics of hosts, parasites and the environment that influence these dynamics. Recent technological advances provide disease ecologists unprecedented ability to track the fine-scale movement of organisms. These, in conjunction with experimental testing of the factors driving infection dynamics during host movement, can inform models of infection spread based on constituent biological processes.
To investigate the link between personality and maximum food intake of inactive individuals, food‐deprived three‐spined sticklebacks Gasterosteus aculeatus at rest in their home compartments were ...provided with ad libitum prey items. Bolder individuals ate considerably more than shyer individuals, even after accounting for body size, while sociability did not have an effect. These findings support pace‐of‐life theory predicting that life‐history strategies are linked to boldness.
Ancient DNA genome-wide analyses of Neolithic individuals from central and southern Europe indicate an overall population turnover pattern in which migrating farmers from Anatolia and the Near East ...largely replaced autochthonous Mesolithic hunter-gatherers. However, the genetic history of the Neolithic transition in areas lying north of the European Neolithic core region involved different levels of admixture with hunter-gatherers. Here we analyse genome-wide data of 17 individuals spanning from the Middle Neolithic to the Early Bronze Age (4300-1900 BCE) in order to assess the Neolithic transition in north-central Poland, and the local impacts of hunter-farmer contacts and Late Neolithic steppe migrations. We evaluate the influence of these on local populations and assess if and how they change through time, reporting evidence of recurrent hunter-farmer admixture over three millennia, and the co-existence of unadmixed hunter-gatherers as late as 4300 BCE. During the Late Neolithic we report the appearance of steppe ancestry, but on a lesser scale than previously described for other central European regions, with evidence of stronger affinities to hunter-gatherers than to steppe pastoralists. These results help understand the Neolithic palaeogenomics of another central European area, Kuyavia, and highlight the complexity of population interactions during those times.
Diving is an ecologically important behaviour that provides air-breathing predators with opportunities to capture prey, but that also increases their exposure to incidental mortality (bycatch) in ...commercial fisheries. In this study, we characterised the diving behaviour of 26 individuals of three species, the black-browed albatross
Thalassarche melanophris,
grey-headed albatross
T. chrysostoma
and light-mantled albatross
Phoebetria palpebrata,
breeding at Bird Island, South Georgia. Individuals were tracked using Global Location Sensor (GLS)-immersion loggers and time-depth recorders (TDRs) and, for two species, Global Positioning System (GPS) loggers. Although the TDRs recorded 589 dives (defined in this paper as submersion > 1 m), average dive depths and durations were just 1.30–1.49 m and 2.5–3.3 s, respectively, for the three species. In addition, many individuals (22% of black-browed, 20% of grey-headed, and 57% of light-mantled albatrosses; total
n
= 9, 10 and 7 individuals, respectively) did not dive at all. Most dives occurred at the distal end of foraging trips and were rare during the commuting phase. No dives took place in darkness, despite long periods spent on water at night. The limited and shallow dive activity contrasts with impressions from a previous study using capillary-tube depth gauges (which are less accurate than TDRs) and has implications for the susceptibility of albatrosses to bycatch on longlines. This study provides further support for regulations requiring night setting and increased sink rates of baited hooks to help mitigate albatross bycatch.
The paper addresses the numerical simulation of strain localisation in stiff clays that exhibit softening behaviour. An elastoplastic constitutive model developed to incorporate key features of stiff ...clay behaviour is described first. A non-local formulation is then introduced for the regularisation of the analysis of localisation. A series of analyses were conducted to explore relevant aspects of the numerical simulation of localisation. A 3D analysis was also performed to assess the suitability of the approach presented for 3D applications. Finally, application to the simulation of a laboratory test on Beaucaire marl results in an excellent reproduction of experimental observations.
Despite widespread recognition of the major threat to tropical forest biological diversity and local food security posed by unsustainable bushmeat hunting, virtually no long-term studies tracking the ...socioecological dynamics of hunting systems have been conducted. We interviewed local hunters and collected detailed hunting data to investigate changes in offtake and hunter characteristics over 10 years (2001-2010) in Dibouka and Kouagna villages, central Gabon, in the context of hunter recollections of longer term trends since the 1950s. To control for changes in hunter behavior, such as trap location and characteristics, we report hunting offtake data per trap. Our results suggest the hunting area was already highly depleted by 2001; local hunters reported that 16 large-bodied prey species had become rare or locally extirpated over the last 60 years. Overall, we observed no significant declines in hunting offtake or changes in species composition from 2001 to 2010, and offtakes per trap increased slightly between 2004 and 2010. However, trapping distance from the villages increased, and there was a switch in hunting techniques; a larger proportion of the catch was hunted with guns in 2010. The number of hunters declined by 20% from 2004 to 2010, and male livelihood activities shifted away from hunting. Hunters with the lowest hunting incomes in 2004 were more likely than successful hunters to have moved away from the village by 2010 (often in response to alternative employment opportunities). Therefore, changes in trap success (potentially related to biological factors) were interacting with system-level changes in hunter number and composition (related to external socioeconomic factors) to produce a relatively static overall offtake. Our results highlight the importance of understanding the small-scale context of hunting to correctly interpret changes or apparent stasis in hunting effort and offtake over time. No obstante el amplio reconocimiento de la amenaza que representa la cacería no sustentable de animales silvestres para la biodiversidad de los bosques tropicales y la seguridad alimentaria local, virtualmente no se han desarrollado estudios a largo plazo sobre la dinámica socioecológica de los sistemas de cacería. Entrevistamos a cazadores locales y recolectamos datos de cacería para investigar cambios en la captura y las características de cazadores a lo largo de 10 años (2001-2010) en las aldeas de Dibouka y Kouaga, Gabón central, en el contexto de remembranzas de cazadores de tendencias a largo plazo desde la década de 1950. Para controlar cambios en la conducta de cazadores, como la localización y características de trampas, reportamos datos de captura por cacería por trampa. Nuestros resultados sugieren que el área de cacería ya estaba agotada en 2001; los cazadores locales reportaron que 16 especies de presas de talla grande se han convertido en raras o han sido extirpadas localmente en los últimos 60 años. En general, no observamos declinaciones significativas en la captura ni cambios en la composición de especies de 2001 a 2010, y las capturas por trampa incrementaron ligeramente entre 2004 y 2010. Sin embargo, la distancia a las trampas desde las aldeas incrementó y hubo un cambio en las técnicas de caza; una mayor proporción de la captura era cazada con armas en 2010. El número de cazadores declinó en 20% de 2004 a 2010, y la actividades de los varones variaron de la cacería. Fue más probable que los cazadores con los menores ingresos por cacería en 2004 se hubieran mudado de la aldea en 2010 que los cazadores exitosos (a menudo una respuesta a oportunidades de empleo alternativo). Por lo tanto, los cambios en el éxito de trampeo (potencialmente relacionado con factores biológicos) interactuaron con cambios a nivel de sistema en el número y composición (relacionada con factores socioeconómicos externos) de cazadores para producir una captura total relativamente estática. Nuestros resultados resaltan la importancia de entender el contexto de la cacería a escala pequeña para interpretar correctamente los cambios o estasis aparente del esfuerzo de caza y la captura a lo largo del tiempo.
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