Resource availability and predation risk influence contest behavior and dominance hierarchies in crayfish

Abstract Degradation of coral reef habitats changes the abundance and community composition of fishes due in part to changes in the ecology of fear. The ecology of fear sees the predator-prey system as a dynamic game of behavioral responses to perceived risk with population and community level consequences. We measure spatial variation in predation risk as landscapes of fear. We consider changes in predation risk with habitat quality and examine the effects of fear on coral reefs in Kāne‘ohe Bay, O‘ahu, Hawai‘i. First, we associate fish and benthic communities on patch reefs with varying degradation due to invasive algae (Euchema spp. and Kappaphycus spp.). Next, we quantify the spatio-temporal variation of risk (reefscape of fear) of a common Hawaiian fish (saddle wrasse, hīnālea lau wili, Thalassoma duperrey) across reefs of varying degradation. Finally, we assess the tradeoffs in resource availability and predation risk on these reefs. At the scale of whole reefs, saddle wrasse responded to perceived risk. Intensity of patch use (measured by giving-up densities) by wrasse indicated risky reefs. Such reefs differed in benthic and fish community composition. We demonstrated the impact of an altered reefscape of fear due to habitat degradation. Habitat degradation seems to influence the tradeoff between resource availability and safety. From wrasse abundances and their patch use behavior we can classify the reefs into categories based on risk and resource availability. Allowing fish to reveal their perceptions of habitat qualities through their behaviors provides critical information for assessing and monitoring reefs.

Download Full-text

Predation and Resource Availability Interact to Drive Life-History Evolution in an Adaptive Radiation of Livebearing Fish

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.619277 ◽

2021 ◽

Vol 9 ◽

Author(s):

Kaj Hulthén ◽

Jacob S. Hill ◽

Matthew R. Jenkins ◽

Randall Brian Langerhans

Keyword(s):

Life History ◽

Predation Risk ◽

Resource Availability ◽

Life Histories ◽

A Priori ◽

Life History Evolution ◽

Selective Agents ◽

Two Factors ◽

High Predation ◽

History Evolution

Predation risk and resource availability are two primary factors predicted by theory to drive the evolution of life histories. Yet, disentangling their roles in life-history evolution in the wild is challenging because (1) the two factors often co-vary across environments, and (2) environmental effects on phenotypes can mask patterns of genotypic evolution. Here, we use the model system of the post-Pleistocene radiation of Bahamas mosquitofish (Gambusia hubbsi) inhabiting blue holes to provide a strong test of the roles of predation and resources in life-history evolution, as the two factors do not co-vary in this system and we attempted to minimize environmental effects by raising eight populations under common laboratory conditions. We tested a priori predictions of predation- and resource-driven evolution in five life-history traits. We found that life-history evolution in Bahamas mosquitofish largely reflected complex interactions in the effects of predation and resource availability. High predation risk has driven the evolution of higher fecundity, smaller offspring size, more frequent reproduction, and slower growth rate—but this predation-driven divergence primarily occurred in environments with relatively high resource availability, and the effects of resources on life-history evolution was generally greater within environments having high predation risk. This implies that resource-driven selection on life histories overrides selection from predators when resources are particularly scarce. While several results matched a priori predictions, with the added nuance of interdependence among selective agents, some did not. For instance, only resource levels, not predation risk, explained evolutionary change in male age at maturity, with more rapid sexual maturation in higher-resource environments. We also found faster (not slower) juvenile growth rates within low-resource and low-predation environments, probably caused by selection in these high-competition scenarios favoring greater growth efficiency. Our approach, using common-garden experiments with a natural system of low- and high-predation populations that span a continuum of resource availability, provides a powerful way to deepen our understanding of life-history evolution. Overall, it appears that life-history evolution in this adaptive radiation has resulted from a complex interplay between predation and resources, underscoring the need for increased attention on more sophisticated interactions among selective agents in driving phenotypic diversification.

Download Full-text

Predation risk and resource abundance mediate foraging behaviour and intraspecific resource partitioning among consumers in dominance hierarchies

10.1101/364182 ◽

2018 ◽

Author(s):

Sean M. Naman ◽

Rui Ueda ◽

Takuya Sato

Keyword(s):

Predation Risk ◽

Resource Partitioning ◽

Population Level ◽

Joint Effect ◽

Masu Salmon ◽

Dominance Hierarchies ◽

Resource Abundance ◽

Size Dependent ◽

Trade Offs ◽

Forest Stream

AbstractDominance hierarchies and unequal resource partitioning among individuals are key mechanisms of population regulation. The strength of dominance hierarchies can be influenced by size dependent trade-offs between foraging and predator avoidance whereby competitively inferior subdominants can access a larger proportion of limiting resources by accepting higher predation risk. Foraging-predation risk trade-offs also depend on resource abundance. Yet, few studies have manipulated predation risk and resource abundance simultaneously; consequently, their joint effect on resource partitioning within dominance hierarchies are not well understood. We addressed this gap by measuring behavioural responses of masu salmon to experimental manipulations of predation risk and resource abundance in a natural temperate forest stream. Responses to predation risk depended on body size such that larger dominants exhibited more risk-averse behaviour (e.g., lower foraging and appearance rates) relative to smaller subdominants after exposure to a simulated predator. The magnitude of this effect was lower when resources were elevated, indicating that dominant fish accepted a higher predation risk to forage on abundant resources. However, the influence of resource abundance did not extend to the population level, where predation risk altered the distribution of foraging attempts (a proxy for energy intake) from being skewed towards large individuals to being skewed towards small individuals after predator exposure. Our results imply that size dependent foraging-predation risk trade-offs can mediate the strength of dominance hierarchies by allowing competitively inferior subdominants to access resources that would otherwise be monopolized.Author Contributions:SN, TS, and RU designed the study and performed the fieldwork; SN analyzed the data and wrote the manuscript with input from all authors.

Download Full-text

Trophic trait plasticity in response to changes in resource availability and predation risk

Functional Ecology ◽

10.1111/j.1365-2435.2011.01891.x ◽

2011 ◽

Vol 25 (6) ◽

pp. 1223-1231 ◽

Cited By ~ 29

Author(s):

Dror Hawlena ◽

Kathy M. Hughes ◽

Oswald J. Schmitz

Keyword(s):

Predation Risk ◽

Resource Availability ◽

Trait Plasticity

Download Full-text

Predation risk breaks size-dependent dominance in juvenile coho salmon (Oncorhynchus kisutch) and provides growth opportunities for risk-prone individuals

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f99-064 ◽

1999 ◽

Vol 56 (7) ◽

pp. 1206-1212 ◽

Cited By ~ 29

Author(s):

Ulrich G Reinhardt

Keyword(s):

Predation Risk ◽

Risk Taking ◽

Coho Salmon ◽

Oncorhynchus Kisutch ◽

Small Fish ◽

Agonistic Interactions ◽

Dominance Hierarchies ◽

Size Dependent ◽

Gain Access ◽

Better Than

Groups of coho salmon (Oncorhynchus kisutch) fry in stream tanks formed size-determined dominance hierarchies, which were upheld through aggressive interactions and led to smaller fish occupying inferior feeding positions. Under simulated predation risk, the frequency of agonistic interactions was reduced, but more intensive aggressive behaviours were performed. This allowed small fish to gain access to better feeding positions. The effect of the predation threat on coho behaviour seemed to extend across a riffle into a second pool that served as a refuge. Smaller fry that chose to be in the exposed pool had greater growth rates than those that mainly occupied the refuge, while large fry that exposed themselves to predation did not grow better than their risk-avoiding counterparts. Differences in risk taking and growth among small coho fry in this experiment may support reports for Atlantic salmon (Salmo salar) of a split into different life history trajectories. The observations suggest that the presence of predators creates opportunities for the expression of alternative behavioural strategies that are absent under size-dependent dominance hierarchies.

Download Full-text

Predation risk and resource availability explain roost locations of WhimbrelNumenius phaeopusin a tropical mangrove delta

Ibis ◽

10.1111/ibi.12678 ◽

2018 ◽

Vol 161 (4) ◽

pp. 839-853 ◽

Cited By ~ 2

Author(s):

Richard Johnston‐González ◽

Elizabeth Abril

Keyword(s):

Predation Risk ◽

Resource Availability

Download Full-text

Measuring Impact of Stress in Sandwich Generation Caring for Demented Parents

GeroPsych ◽

10.1024/1662-9647/a000114 ◽

2014 ◽

Vol 27 (4) ◽

pp. 171-179 ◽

Cited By ~ 6

Author(s):

Laurence M. Solberg ◽

Lauren B. Solberg ◽

Emily N. Peterson

Keyword(s):

Factor Analysis ◽

Exploratory Factor Analysis ◽

Social Worker ◽

Resource Availability ◽

Well Being ◽

Sandwich Generation ◽

Item Questionnaire ◽

Significant Difference ◽

Adult Caregivers ◽

The Impact

Stress in caregivers may affect the healthcare recipients receive. We examined the impact of stress experienced by 45 adult caregivers of their elderly demented parents. The participants completed a 32-item questionnaire about the impact of experienced stress. The questionnaire also asked about interventions that might help to reduce the impact of stress. After exploratory factor analysis, we reduced the 32-item questionnaire to 13 items. Results indicated that caregivers experienced stress, anxiety, and sadness. Also, emotional, but not financial or professional, well-being was significantly impacted. There was no significant difference between the impact of caregiver stress on members from the sandwich generation and those from the nonsandwich generation. Meeting with a social worker for resource availability was identified most frequently as a potentially helpful intervention for coping with the impact of stress.

Download Full-text

Social development of modern Russia: trends, risks, prospects

Voprosy Ekonomiki ◽

10.32609/0042-8736-2018-10-76-89 ◽

2018 ◽

pp. 76-89

Author(s):

E. M. Avraamova ◽

V. N. Titov

Keyword(s):

Middle Class ◽

Social Development ◽

Social Structure ◽

Structure Formation ◽

Resource Availability ◽

Social Dynamics ◽

Quantitative Estimation ◽

Resource Potential ◽

Institutional Conditions ◽

Resource Characteristics

The analysis of present-time directions in the study of social development has allowed to identify the resource approach as the most productive one which enables to assess social dynamics through the range of resource characteristics of different population groups and abilities of the relevant groups to apply development resources in the current economic and institutional conditions. Basing on the sociological survey conducted by ISAP RANEPA, the quantitative estimation of material and social recourses of the population has been made; integral values of the resource potential have been calculated as well. The issues of social structure formation are analyzed through the aspect of resource availability; the barriers of Russian middle-class enlargement are defined.

Download Full-text