Long-term inference of population size and habitat use in a socially dynamic population of wild western lowland gorillas

Chronic environmental change threatens biodiversity, but acute disturbance events present more rapid and immediate threats. In 2010, a cold snap across south Florida had wide-ranging impacts, including negative effects on recreational fisheries, agriculture, and ecological communities. Here, we use acoustic telemetry and historical longline monitoring to assess the long-term implications of this event on juvenile bull sharks Carcharhinus leucas in the Florida Everglades. Despite the loss of virtually all individuals (ca. 90%) within the Shark River Estuary during the cold snap, the catch per unit effort (CPUE) of age 0 sharks on longlines recovered through recruitment within 6-8 mo of the event. Acoustic telemetry revealed that habitat use patterns of age 0-2 sharks reached an equilibrium in 4-6 yr. In contrast, the CPUE and habitat use of age 3 sharks required 5-7 yr to resemble pre-cold snap patterns. Environmental conditions and predation risk returned to previous levels within 1 yr of the cold snap, but abundances of some prey species remained depressed for several years. Reduced prey availability may have altered the profitability of some microhabitats after the cold snap, leading to more rapid ontogenetic shifts to marine waters among sharks for several years. Accelerated ontogenetic shifts coupled with inter-individual behavioral variability of bull sharks likely led to a slower recovery rate than predicted based on overall shark CPUE. While intrinsic variation driven by stochasticity in dynamic ecosystems may increase the resistance of species to chronic and acute disturbance, it may also increase recovery time in filling the diversity of niches occupied prior to disturbance if resistive capacity is exceeded.

Download Full-text

Update on the Boundaries of the Curly Birch Range

Lesnoy Zhurnal (Forestry Journal) ◽

10.37482/0536-1036-2020-6-9-21 ◽

2020 ◽

pp. 9-21

Author(s):

L.V. Vetchinnikova ◽

◽

A.F. Titov ◽

◽

Keyword(s):

Population Size ◽

Natural Populations ◽

Forest Tree ◽

Published Data ◽

Population Approach ◽

Key Factors ◽

History Of ◽

Individual Trees ◽

Karelian Birch

The article reports on the application of the best known principles for mapping natural populations of curly (Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti – one of the most appealing representatives of the forest tree flora. Relying on the synthesis and analysis of the published data amassed over nearly 100 years and the data from own full-scale studies done in the past few decades almost throughout the area where curly birch has grown naturally, it is concluded that its range outlined in the middle of the 20th century and since then hardly revised is outdated. The key factors and reasons necessitating its revision are specified. Herewith it is suggested that the range is delineated using the population approach, and the key element will be the critical population size below which the population is no longer viable in the long term. This approach implies that the boundaries of the taxon range depend on the boundaries of local populations (rather than the locations of individual trees or small clumps of trees), the size of which should not be lower than the critical value, which is supposed to be around 100–500 trees for curly birch. A schematic map of the curly birch range delineated using this approach is provided. We specially address the problem of determining the minimum population size to secure genetic diversity maintenance. The advantages of the population approach to delineating the distribution range of curly birch with regard to its biological features are highlighted. The authors argue that it enables a more accurate delineation of the range; shows the natural evolutionary history of the taxon (although it is not yet officially recognized as a species) and its range; can be relatively easily updated (e.g. depending on the scope of reintroduction); should be taken into account when working on the strategy of conservation and other actions designed to maintain and regenerate this unique representative of the forest tree flora.

Download Full-text

Can we reestablish a self-sustaining population? A case study on reintroduced Crested Ibis with population viability analysis

Avian Research ◽

10.1186/s40657-021-00250-z ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yashuai Zhang ◽

Fang Wang ◽

Zhenxia Cui ◽

Min Li ◽

Xia Li ◽

...

Keyword(s):

Sex Ratio ◽

Population Size ◽

Carrying Capacity ◽

Wild Population ◽

Population Viability Analysis ◽

Population Viability ◽

Viability Analysis ◽

Crested Ibis ◽

Reintroduced Population

Abstract Background One of the most challenging tasks in wildlife conservation and management is clarifying which and how external and intrinsic factors influence wildlife demography and long-term viability. The wild population of the Crested Ibis (Nipponia nippon) has recovered to approximately 4400, and several reintroduction programs have been carried out in China, Japan and Korea. Population viability analysis on this endangered species has been limited to the wild population, showing that the long-term population growth is restricted by the carrying capacity and inbreeding. However, gaps in knowledge of the viability of the reintroduced population and its drivers in the release environment impede the identification of the most effective population-level priorities for aiding in species recovery. Methods The field monitoring data were collected from a reintroduced Crested Ibis population in Ningshan, China from 2007 to 2018. An individual-based VORTEX model (Version 10.3.5.0) was used to predict the future viability of the reintroduced population by incorporating adaptive patterns of ibis movement in relation to catastrophe frequency, mortality and sex ratio. Results The reintroduced population in Ningshan County is unlikely to go extinct in the next 50 years. The population size was estimated to be 367, and the population genetic diversity was estimated to be 0.97. Sensitivity analysis showed that population size and extinction probability were dependent on the carrying capacity and sex ratio. The carrying capacity is the main factor accounting for the population size and genetic diversity, while the sex ratio is the primary factor responsible for the population growth trend. Conclusions A viable population of the Crested Ibis can be established according to population viability analysis. Based on our results, conservation management should prioritize a balanced sex ratio, high-quality habitat and low mortality.

Download Full-text

Fecal glucocorticoids and gastrointestinal parasite infections in wild western lowland gorillas (Gorilla gorilla gorilla) involved in ecotourism

General and Comparative Endocrinology ◽

10.1016/j.ygcen.2021.113859 ◽

2021 ◽

pp. 113859

Author(s):

Kathryn Shutt-Phillips ◽

Barbora Pafčo ◽

Michael Heistermann ◽

Adetayo Kasim ◽

Klára J. Petrželková ◽

...

Keyword(s):

Gorilla Gorilla ◽

Gastrointestinal Parasite ◽

Gorilla Gorilla Gorilla ◽

Parasite Infections ◽

Western Lowland Gorillas ◽

Fecal Glucocorticoids ◽

Lowland Gorillas

Download Full-text

Agglomeration economies, congestion diseconomies, and fertility dynamics in a two-region economy

Letters in Spatial and Resource Sciences ◽

10.1007/s12076-020-00264-z ◽

2021 ◽

Author(s):

Madoka Muroishi ◽

Akira Yakita

Keyword(s):

Population Size ◽

Stability Condition ◽

Fertility Rate ◽

Model Parameters ◽

Initial Population ◽

Interregional Migration ◽

Stable Path ◽

Regional Population ◽

Initial Population Size

AbstractUsing a small, open, two-region economy model populated by two-period-lived overlapping generations, we analyze long-term agglomeration economy and congestion diseconomy effects of young worker concentration on migration and the overall fertility rate. When the migration-stability condition is satisfied, the distribution of young workers between regions is obtainable in each period for a predetermined population size. Results show that migration stability does not guarantee dynamic stability of the economy. The stationary population size stability depends on the model parameters and the initial population size. On a stable trajectory converging to the stationary equilibrium, the overall fertility rate might change non-monotonically with the population size of the economy because of interregional migration. In each period, interregional migration mitigates regional population changes caused by fertility differences on the stable path. Results show that the inter-regional migration-stability condition does not guarantee stability of the population dynamics of the economy.

Download Full-text