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opencc-zeroDec 2023View details →

Genomic footprints of (pre) colonialism: Population declines in urban and forest túngara frogs coincident with historical human activity

Urbanisation is rapidly altering ecosystems, leading to profound biodiversity loss. To mitigate these effects, we need a better understanding of how urbanisation impacts dispersal and reproduction. Two contrasting population demographic models have been proposed that predict that urbanisation either promotes (facilitation model) or constrains (fragmentation model) gene flow and genetic diversity. Which of these models prevails likely depends on the strength of selection on specific phenotypic traits that influence dispersal, survival, or reproduction. Here, we a priori examined the genomic impact of urbanisation on the Neotropical túngara frog (Engystomops pustulosus), a species known to adapt its reproductive traits to urban selective pressures. Using whole-genome resequencing for multiple urban and forest populations we examined genomic diversity, population connectivity and demographic history. Contrary to both the fragmentation and facilitation models, urban populations did not exhibit substantial changes in genomic diversity or differentiation compared to forest populations, and genomic variation was best explained by geographic distance rather than environmental factors. Adopting an a posteriori approach, we additionally found both urban and forest populations to have undergone population declines. The timing of these declines appears to coincide with extensive human activity around the Panama Canal during the last few centuries rather than recent urbanisation. Our study highlights the long-lasting legacy of past anthropogenic disturbances in the genome and the importance of considering the historical context in urban evolution studies as anthropogenic effects may be extensive and impact non-urban areas on both recent and older timescales.

opencc-zeroAug 2022View details →

Differential changes in lifecycle-event phenology provide a window into regional population declines

Climate change affects the phenology of annual lifecycle events of organisms, such as reproduction and migration. Shifts in the timing of these events could have important population implications directly, or provide information about the mechanisms driving population trajectories, especially if they differ between lifecycle event. We examine if such shifts occur in a declining migratory passerine bird (Willow Warbler, Phylloscopus trochilus), which exhibits latitudinally diverging population trajectories. We find evidence of phenological shifts in breeding initiation, breeding progression and moult that differ across geographic and spring temperature gradients. Moult initiation following warmer springs advances faster in the south than in the north, resulting in proportionally shorter breeding seasons, reflecting higher nest failure rates in the south and in warmer years. Tracking shifts in multiple lifecycle events allowed us to identify points of failure in the breeding cycle in regions where the species has negative population trends, thereby demonstrating the utility of phenology analyses for illuminating mechanistic pathways underlying observed population trajectories.

opencc-zeroSep 2022View details →

Temporal change in the contribution of immigration to population growth in a wild seabird experiencing rapid population decline

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.

opencc-zeroOct 2022View details →

Data from: Protection status, human disturbance, snow cover and trapping drive density of a declining wolverine population in the Canadian Rocky Mountains

Protected areas are important in species conservation, but high rates of human-caused mortality outside their borders and increasing popularity for recreation can negatively affect wildlife populations. We quantified wolverine (Gulo gulo) population trends from 2011 to 2020 in >14 000 km2 protected and non-protected habitat in southwestern Canada. We conducted wolverine and multi-species surveys using non-invasive DNA and remote camera-based methods. We developed Bayesian integrated models combining spatial capture-recapture data of marked and unmarked individuals with occupancy data. Wolverine density and occupancy declined by 39 percent, with an annual population growth rate of 0.925. Density within protected areas was 3 times higher than outside and declined between 2011 (3.6 wolverines/1000 km2) and 2020 (2.1 wolverines/1000 km2). Wolverine density and detection probability increased with snow cover and decreased near development. Detection probability also decreased with human recreational activity. The annual harvest rate of 13% was above the maximum sustainable rate. We conclude that humans negatively affected the population through direct mortality, sub-lethal effects and habitat impacts. Our study exemplifies the need to monitor population trends for species at risk – within and between protected areas - as steep declines can occur unnoticed if key conservation concerns are not identified and addressed.

Fig. 5 in Age Structure In A Declining Population Of Rana Temporaria From Northern Italy

Fig. 5. Relationship between age and body length in male (filled circles) and female (empty circles) Rana temporaria

Fig. 3 in Age Structure In A Declining Population Of Rana Temporaria From Northern Italy

Fig. 3. Diaphyseal cross-sections of phalanges of Rana temporaria females. (a) Individual, 70 mm in body length, with 1 visible LAG plus one confluent with the outer margin of periosteal bone. Some false lines are also present. (b) Individual, 73.2 mm in body length, with 2 visible LAGs plus one confluent with the outer margin of periosteal bone. (c) Individual, 85.7 mm in body length, with 5 LAGs. (d) Individual, 101 mm in body length, with 7 LAGs. (e) Individual, 120 mm in body length, with the first 4 but not the peripheral LAGs clearly distinguishable. (f) Same individual as in the previous figure but adjacent section at higher magnification showing 6 distinct LAGs at the periphery of periosteal bone. Based on these observations it is concluded that this frog had 10 LAGs. Abbreviations: EB = endosteal bone; MC = medullar cavity; RL = reversal line; VC = vascular canal. Arrows indi-

Fig. 2 in Age Structure In A Declining Population Of Rana Temporaria From Northern Italy

Fig. 2. Diaphyseal cross-sections of phalanges of Rana temporaria males. (a) Juvenile, 50.1 mm in body length, without LAGs. (b) Individual, 63 mm in body length, with 1 visible LAG plus one nonvisible probably because it is confluent with the outer margin of periosteal bone. (c) Individual, 74.7 mm in body length, with 6 LAGs. (d) Same individual as in Fig. 2c but at higher magnification. 5 LAGs can be more easily counted in the ridge at the periphery of periosteal bone. (e) Individual, 85.2 mm in body length, with 8 LAGs. (f) Individual, 89 mm in body length, with 10 LAGs, of which the peripheral are very close to each other. Abbreviations: EB = endosteal bone; MC = medullar cavity; RL = reversal line. Arrows indicate lines of arrested growth (LAGs). Scale bar, 100 µm in Figs 2a–e;

Fig. 1 in Age Structure In A Declining Population Of Rana Temporaria From Northern Italy

Fig. 1. Body length distribution (2 mm classes) of male (filled bars) and female (empty bars) Rana temporaria. The dotted bar represents a juvenile male

Figure 4. A cove with shallow water near Ponte Porton with 14 in Populations of Microcondylaea bonellii (Férussac 1827), Unionidae - an european freshwater mussel at rapid decline - and Unio mancus in Istria, Croatia

Figure 4. A cove with shallow water near Ponte Porton with 14 individuals of Microcondylaea bonellii (26.9.2009).

Figure 3 in Populations of Microcondylaea bonellii (Férussac 1827), Unionidae - an european freshwater mussel at rapid decline - and Unio mancus in Istria, Croatia

Figure 3. Numbers of shells of Unio mancus (blue) and Microcondylaea bonelli at the different sites (red).

Fig. 2 and 3 in Populations of Microcondylaea bonellii (Férussac 1827), Unionidae - an european freshwater mussel at rapid decline - and Unio mancus in Istria, Croatia

Fig. 2 and 3 give the results of my surveys in river Mirna in 2009 to 2016. In the upper part of the river from the city of Buzet to the confluence with Butoniga the artificially straightened riverbed is dominated by coarse gravel and shows ± rapid current. Although Microcondylaea was recorded from this part of the river near Istarske Teplice (Fischer 1999) no shells or living specimens were found actually. Populations of Unio mancus were mainly found in tributaries like Bračana and drenches, less frequently in the riverbed of upper Mirna. Between 2009 and 2016 the Mirna-riverbed was reconstructed in several places, eroded banks with coves and fine sand substrate were replaced by blocks of stone and the riverbed straightened again. Thus many suitable habitats and eventually existing mussels-populations were destroyed, so much the worse as heavy machines were driving in the riverbed over many weeks for the construction works and mobilized the substrate, which led to high accumulations of fine sediment in the lower part of the river, especially in parts with low current and coves which were inhabited by Microcondylaea.

Figure 1 in Populations of Microcondylaea bonellii (Férussac 1827), Unionidae - an european freshwater mussel at rapid decline - and Unio mancus in Istria, Croatia

Figure 1. Map of known living populations of Microcondylaea bonelli in Slovenia (grey) and Italy (yellow) from http://art17.eionet.europa.eu/article17/reports2012/species/summary/. Populations in Croatia (red) added by the author.

opencc-zeroJul 2024View details →

Data from: Widespread cultural change in declining populations of Amazon parrots

This dataset of parrot call measurements and metadata is associated with the article "Widespread cultural change in declining populations of Amazon parrots" in Proceedings of the Royal Society B. The data was used to address change and stability in regional vocal dialects of yellow-naped amazon (Amazona auropalliata) contact calls recorded in Costa Rica over three sampling periods that spanned 22 years.

opencc-by-4.0Dec 2013View details →

Fig. 11 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)

Fig. 11. Transmission electron micrograph of an epimastigote and an amastigote of G2 (Clade A). (A) Epimastigote in culture; Ax: Axoneme showing nine doublets of microtubules surrounding a central pair; Ac: Acidocalcisomes; Arrow: Subpellicular microtubules. (B) Amastigote inside a VERO cell. Scale bars = 0.5 µm (A), 1 µm (B).

opencc-by-4.0Dec 2013View details →

Fig. 9 in Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)

Fig. 9. Infection of Vero (A) and L6 cells (B) with G2 (Clade A) and T. cruzi as a positive control of infection (Diff-Quick stained). (A) Intracellular amastigotes of G2. (B) Intracellular amastigotes of T. cruzi. Scale bars = 10 µm.