The impact of calcium decline on population growth rates of crustacean zooplankton in Canadian Shield lakes

2017 ◽  
Vol 63 (2) ◽  
pp. 602-616 ◽  
Author(s):  
Shakira S. E. Azan ◽  
Shelley E. Arnott
Keyword(s):  
Population Growth ◽  
Growth Rates ◽  
Canadian Shield ◽  
Crustacean Zooplankton ◽  
Population Growth Rates ◽  
Calcium Decline ◽  
Shield Lakes ◽  
The Impact

scholarly journals Founder effects drive the genetic structure of passively dispersed aquatic invertebrates

2018 ◽  
Author(s):  
Javier Montero-Pau ◽  
Africa Gomez ◽  
Manuel Serra
Keyword(s):  
Life Cycle ◽  
Genetic Structure ◽  
Population Growth ◽  
Local Adaptation ◽  
Growth Rates ◽  
High Population ◽  
Founder Effects ◽  
Population Growth Rates ◽  
High Population Growth ◽  
The Impact

Populations of passively dispersed organisms in continental aquatic habitats typically show high levels of neutral genetic differentiation, despite their high dispersal capabilities. Several evolutionary factors, including founder events and local adaptation, and life cycle features such as high population growth rates and the presence of propagule banks, have been proposed to be responsible for this paradox. Here, we have modeled the colonization process in these organisms to assess the impact of migration rate, growth rate, population size, local adaptation and life-cycle features on their population genetic structure. Our simulation results show that the strongest effect on population structure is caused by persistent founder effects, resulting from the interaction of a few population founders, high population growth rates, large population sizes and the presence of diapausing egg banks. In contrast, the role of local adaptation, genetic hitchhiking and migration is limited to small populations in these organisms. Our results indicate that local adaptation could have different impact on genetic structure in different groups of zooplankters.

Will environmental calcium declines hinder Bythotrephes establishment success in Canadian Shield lakes?

2012 ◽  
Vol 69 (5) ◽  
pp. 810-820 ◽  
Author(s):  
Natalie Kim ◽  
Bjørn Walseng ◽  
Norman David Yan
Keyword(s):  
Lake Water ◽  
Calcium Content ◽  
Dry Mass ◽  
Canadian Shield ◽  
Direct Effects ◽  
Bythotrephes Longimanus ◽  
Establishment Success ◽  
Population Growth Rates ◽  
Calcium Decline ◽  
Shield Lakes

Recently, calcium-rich daphniids have declined on the Canadian Shield in response to falling lake-water calcium concentrations, or [Ca]. Meanwhile the invader Bythotrephes longimanus , a predator that feeds on Daphnia , continues to spread. Our goal was to determine if ongoing calcium declines might directly or indirectly affect Bythotrephes ’ establishment success. To address direct effects, we provide the first quantification of Bythotrephes’ calcium content, which is very low (0.03% as dry mass) compared with other Cladocera. We also examined the effects of differing [Ca] (0.1–2.6 mg·L–1) on Bythotrephes’ performance in the laboratory. For all [Ca], population growth rates remained positive, indicating that Bythotrephes has great tolerance of low [Ca]. Finally, we examined Bythotrephes’ distribution in relation to [Ca] on the Shield where is it relatively new, alongside its distribution in Norway where it is endemic and found that Bythotrephes inhabits very low calcium environments in Norway (minimum = 0.2 mg·L–1). These results suggest that Bythotrephes establishment in Canada is currently not — and in the future will likely not — be limited by falling calcium. Rather, as Bythotrephes is more tolerant of low [Ca] than are its daphniid prey, we propose that both calcium decline and Bythotrephes invasions may contribute to Daphnia decline.

Road mortality reduces survival and population growth rates of tammar wallabies on Garden Island, Western Australia

2010 ◽  
Vol 37 (7) ◽  
pp. 588 ◽  
Author(s):  
Brian Chambers ◽  
Roberta Bencini
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Western Australia ◽  
Growth Rates ◽  
Survival Rates ◽  
Habitat Modification ◽  
Road Mortality ◽  
Population Growth Rates ◽  
The Impact ◽  
Naval Base

Context Although road mortality has the potential to affect the fate of populations, it is often confounded with other forms of environmental change. Therefore determining its impact separately from other factors is difficult because it requires an understanding of how road mortalities affect age- and sex-specific survival rates. Aims We determined the impact of high numbers of road-kills and habitat modification on the growth and survival of the population of tammar wallabies (Macropus eugenii) on Garden Island, off the coast of Western Australia. The increased supply of food from large areas of fertilised and irrigated lawns on a naval base was expected to increase the population growth rate (λ) and the road-kills were expected to offset the population response. Methods We conducted a mark-and-recapture study over three years to estimate rates of survival, reproduction and population growth rates in areas of the island that were either heavily affected by the presence of a naval base that included a network of roads and buildings, close enough to the naval base that animals could be affected by the disturbance there, and completely unaffected and lacking major roads or buildings. All road-kills were collected to estimate the impact of road mortality on the survival and growth rates of the population. Key results The growth rate, λ, for the population on the naval base was 1.02 ± 0.083 (s.e.) per year, which was much higher than in an area of adjacent bushland at 0.92 ± 0.065 per year and in undisturbed bushland at 0.93 ± 0.100 per year. When the impact of road mortality was removed, λ increased to 1.15 ± 0.101 per year on the naval base and 0.96 ± 0.076 per year in the bushland adjacent to the naval base. On the naval base road mortality reduced survival rates of one-year-old and adult animals by 0.14 ± 0.087 and 0.12 ± 0.012 per year (mean ± s.e.). Conclusions Road mortality counteracted the increase in the size of the tammar population caused by the habitat modification on the naval base. The impact of road mortality on the adjacent bushland population may result in its long-term decline, as the population may not be able to recover from the reduction in survival rates. Implications Road mortality has the potential to threaten susceptible populations but its impact should be quantified so that mitigation measures can be implemented where they will achieve the greatest benefits.

scholarly journals Founder effects drive the genetic structure of passively dispersed aquatic invertebrates

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e6094 ◽  
Author(s):  
Javier Montero-Pau ◽  
Africa Gómez ◽  
Manuel Serra
Keyword(s):  
Life Cycle ◽  
Genetic Structure ◽  
Population Growth ◽  
Local Adaptation ◽  
Growth Rates ◽  
High Population ◽  
Founder Effects ◽  
Population Growth Rates ◽  
High Population Growth ◽  
The Impact

Populations of passively dispersed organisms in continental aquatic habitats typically show high levels of neutral genetic differentiation despite their high dispersal capabilities. Several evolutionary factors, including founder events, local adaptation, and life cycle features such as high population growth rates and the presence of propagule banks, have been proposed to be responsible for this paradox. Here, we have modeled the colonization process to assess the impact of migration rate, population growth rate, population size, local adaptation and life-cycle features on the population genetic structure in these organisms. Our simulations show that the strongest effect on population structure are persistent founder effects, resulting from the interaction of a few population founders, high population growth rates, large population sizes and the presence of diapausing egg banks. In contrast, the role of local adaptation, genetic hitchhiking and migration is limited to small populations in these organisms. Our results indicate that local adaptation could have different impact on genetic structure in different groups of zooplankters.

scholarly journals Founder effects drive the genetic structure of passively dispersed aquatic invertebrates

2018 ◽  
Author(s):  
Javier Montero-Pau ◽  
Africa Gomez ◽  
Manuel Serra
Keyword(s):  
Life Cycle ◽  
Genetic Structure ◽  
Population Growth ◽  
Local Adaptation ◽  
Growth Rates ◽  
High Population ◽  
Founder Effects ◽  
Population Growth Rates ◽  
High Population Growth ◽  
The Impact

Populations of passively dispersed organisms in continental aquatic habitats typically show high levels of neutral genetic differentiation, despite their high dispersal capabilities. Several evolutionary factors, including founder events and local adaptation, and life cycle features such as high population growth rates and the presence of propagule banks, have been proposed to be responsible for this paradox. Here, we have modeled the colonization process in these organisms to assess the impact of migration rate, growth rate, population size, local adaptation and life-cycle features on their population genetic structure. Our simulation results show that the strongest effect on population structure is caused by persistent founder effects, resulting from the interaction of a few population founders, high population growth rates, large population sizes and the presence of diapausing egg banks. In contrast, the role of local adaptation, genetic hitchhiking and migration is limited to small populations in these organisms. Our results indicate that local adaptation could have different impact on genetic structure in different groups of zooplankters.

The use of contraceptive techniques in managed wild African lion (Panthera leo) populations to mimic open system cub recruitment

2019 ◽  
Vol 46 (5) ◽  
pp. 398 ◽  
Author(s):  
Orla K. McEvoy ◽  
Susan M. Miller ◽  
Warren Beets ◽  
Tarik Bodasing ◽  
Natalia Borrego ◽  
...  
Keyword(s):  
Side Effects ◽  
Population Growth ◽  
Protected Areas ◽  
Litter Size ◽  
Open System ◽  
Growth Rates ◽  
Panthera Leo ◽  
Population Growth Rates ◽  
Post Surgery ◽  
The Impact

Context Managed wild lions (Panthera leo) are lions found in smaller (<1000 km2), fenced protected areas that hold a substantial portion of South Africa’s wild lion population. Because the natural population control mechanisms are compromised within these properties, managers must actively control population growth rates. Fecundity control is used by wildlife managers, but long-term, empirical data on the impact and consequences of such interventions in lions are lacking. Aims The aim of the present study was to assess the effectiveness of two methods of contraception (deslorelin implant and unilateral hysterectomy) in reducing cub recruitment of managed wild lions. Methods Survey data spanning 14 years from 94 managed wild lions on 19 protected areas were used to evaluate the effectiveness of deslorelin implant treatments and unilateral hysterectomies on population growth rates through mimicking open system cub recruitment. Key results Deslorelin implants were effective at increasing the age of first reproduction and lengthening inter-birth intervals. There was also an unexpected decrease in litter size. Behavioural side-effects were recorded in 40% of individuals: 19% pride fragmentation; 13% lack of receptiveness towards males; 8% other. The more successive deslorelin implants a lioness had, the more likely it was that weight gain was reported. Unilateral hysterectomy resulted in a decrease in litter size post-surgery, but this was not statistically significant. No behavioural or physiological side-effects were noted after unilateral hysterectomy. Conclusions Deslorelin treatment was more effective in reducing the reproductive output of managed wild lionesses than unilateral hysterectomy surgery. While more side-effects were associated with deslorelin implants than unilateral hysterectomies, a single deslorelin treatment is currently a good option for fecundity reduction. More research is required on unilateral hysterectomy surgery. Implications Neither deslorelin implants nor unilateral hysterectomies offer a ‘silver bullet’ solution for reducing rapid population growth in managed wild lions. Reproductive control should be integrated with other best-practice approaches.

scholarly journals The impact of human activity on anthropogenic dust emission over global semi-arid regions

2016 ◽  
Author(s):  
X. Guan ◽  
J. Huang ◽  
Y. Zhang ◽  
Y. Xie ◽  
J. Liu
Keyword(s):  
Population Growth ◽  
Growth Rates ◽  
Human Activities ◽  
Arid Regions ◽  
Population Change ◽  
Dust Emission ◽  
Dust Production ◽  
Population Growth Rates ◽  
The Impact ◽  
Semi Arid

Abstract. Anthropogenic dust is acknowledged as a product of human activities on disturbed soil, and is generated mainly from sensitive and fragile regions including croplands, pastures, and urbanized regions. In this study, we analyzed the behaviour of anthropogenic dust in semi-arid region of globe, and its relationship to human activities. An obvious peak in the total anthropogenic dust column, much higher magnitude than those of wet regions, was observed in semi-arid regions with population growth rates of more than 11.46 %. Four typical semi-arid regions, East China, India, North America and North Africa were selected to explore the local difference in anthropogenic dust production. The population growth rates in these areas were approximately 6.16 %, 17.71 %, 11.21 %, and 29.26 %, and the anthropogenic dust levels were 0.17 g m−2, 0.38 g m−2, 0.10 g m−2 and 0.21 g m−2, which are higher than the natural dust column burden. The anthropogenic dust column burden is positively correlated with the population and population change, indicating a contribution from human activities to the anthropogenic dust production. Based on the fact that anthropogenic dust can act as warming aerosol, the radiative effect of anthropogenic dust in semi-arid regions can not be ignored and requires further investigation.

scholarly journals Founder effects drive the genetic structure of passively dispersed aquatic invertebrates

2017 ◽  
Author(s):  
Javier Montero-Pau ◽  
Africa Gomez ◽  
Manuel Serra
Keyword(s):  
Life Cycle ◽  
Genetic Structure ◽  
Population Growth ◽  
Local Adaptation ◽  
Growth Rates ◽  
High Population ◽  
Founder Effects ◽  
Population Growth Rates ◽  
High Population Growth ◽  
The Impact

Populations of passively dispersed organisms in continental aquatic habitats typically show high levels of neutral genetic differentiation, despite their high dispersal capabilities. Several evolutionary factors, including founder events and local adaptation, and life cycle features such as high population growth rates and the presence of propagule banks, have been proposed to be responsible for this paradox. Here, we have modeled the colonization process in these organisms to assess the impact of migration rate, growth rate, population size, local adaptation and life-cycle features on their population genetic structure. Our simulation results show that the strongest effect on population structure is caused by persistent founder effects, resulting from the interaction of a few population founders, high population growth rates, large population sizes and the presence of diapausing egg banks. In contrast, the role of local adaptation, genetic hitchhiking and migration is limited to small populations in these organisms. Our results indicate that local adaptation could have different impact on genetic structure in different groups of zooplankters.

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