Related Experiment Video
Updated: Aug 14, 2025
07:41
Modeling the Size Spectrum for Macroinvertebrates and Fishes in Stream Ecosystems
Published on: July 30, 2019
7.5K
Resource availability modulates the effect of body size on reproductive development
Réka Gergely1,2, Jácint Tökölyi1
1MTA-DE "Momentum" Ecology, Evolution and Developmental Biology Research Group, Department of Evolutionary Zoology University of Debrecen Debrecen Hungary.
Ecology and Evolution
|January 9, 2023
Summary
Large body size in Hydra oligactis provides energy reserves, influencing reproduction and survival. Small individuals are sensitive to food availability but can adjust development to maintain fitness.
Area of Science:
- Ecology
- Evolutionary Biology
- Animal Physiology
Background:
- Body size variation impacts animal life history traits like reproduction and longevity.
- Two hypotheses explain size-fitness correlations: energy reserves (large size = better fitness) or energy demand (large size = worse fitness under scarcity).
- Distinguishing these hypotheses is challenging due to confounding factors like resource availability during growth.
Purpose of the Study:
- To experimentally disentangle the direct effects of body size from resource availability on fitness traits in Hydra oligactis.
- To test the energy reserve versus energy demand hypotheses in a model organism.
- To investigate sex-specific responses to body size and food availability.
Main Methods:
- Experimental manipulation of body size in Hydra oligactis.
- Manipulation of resource (food) availability.
- Assessment of fitness traits: sexual development time, fecundity, and survival.
Main Results:
- A significant interaction between body size and food availability affected sexual development time in both sexes, with large individuals showing less response to food variation.
- These findings support an energy reserve effect of large body size in Hydra.
- Small individuals showed sensitivity to food availability, with sex-specific reproductive development adjustments (females delayed, males accelerated).
- Both body size and food availability impacted fecundity and survival, but without interaction.
Conclusions:
- Large body size in Hydra oligactis appears to confer an advantage through energy reserves, buffering against resource fluctuations.
- Small individuals exhibit plasticity in reproductive development in response to food availability, enabling fitness maintenance.
- The study highlights sex-specific responses to environmental conditions mediated by body size.
Related Concept Videos
00:51Energy Budgets
9.6K
Organisms must balance energy intake with the energy required for growth, maintenance and reproduction. These trade-offs result in a variety of survivorship and reproductive strategies, including semelparity and iteroparity. Semelparous species, like annual plants, have only one reproductive episode in their lifetimes and consequently have short lifespans. Iteroparous species, by contrast, have many reproductive events during their lifetimes but have relatively few offspring. These two...
9.6K
01:29Life Histories
18.4K
Overview
18.4K
01:06Natural Selection and Mating Preferences
153
The principle of natural selection posits that organisms better adapted to their environment are more likely to survive and reproduce. This principle is closely intertwined with mating preferences, a key aspect of sexual selection, which evolutionary psychologists believe is driven by instincts to propagate one's genes. Such instincts significantly influence mating behaviors and preferences between genders.
Females, due to their biological roles in conception, pregnancy, and nursing,...
Females, due to their biological roles in conception, pregnancy, and nursing,...
153
02:27Background and Environment Affect Phenotype
6.6K
Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as temperature, oxygen availability, presence of mutagens, that can alter an organism’s phenotype.
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
6.6K
02:36Cells Coordinate Growth and Proliferation
4.6K
Cell size is a significant factor impacting cellular design, function, and fitness. There exists some internal coordination by which cells double their masses before division, thus, achieving homeostasis. Coordination between cell growth and proliferation depends on the checkpoints in between cell cycle phases. Loss of coordination or failure in the checkpoint mechanism can drive the cell to uncontrolled growth and loss of cellular function. Like dividing cells that coordinate cellular growth,...
4.6K
01:10Nature and Nurture
20.6K
Many human characteristics, like height, are shaped by both nature—in other words, by our genes—and by nurture, or our environment. For example, chronic stress during childhood inhibits the production of growth hormones and consequently reduces bone growth and height. Scientists estimate that 70-90% of variation in height is due to genetic differences among individuals, and 10-30% of variation in height is due to differences in the environments that individuals experience,...
20.6K