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Changes in the brain: How do hormones influence social status in Astatotilapia burtoni?
Astatotilapia burtoni is a fish that lives in Lake Tanganyika and its surrounding waters. It belongs to the family Cichlidae and is widely distributed in Burundi, Rwanda, Tanzania and Zambia. The ecological environment of these fishes includes natural habitats such as rivers, swamps and freshwater lakes. Due to its special taxonomic status, A. burtoni has also become a model organism for studying the behavioral and physiological systems of cichlids, especially their development and embryonic development. This fish is a unique haploid species that is closely related to the diversity of Lake Victoria and Lake Malawi.
Social Behavior
Reversible male social roles
Male fish of Astatotilapia burtoni have two reversible phenotypes. These males can rapidly switch between territorial and non-territorial states when social circumstances change. Territorial males have bright colors and aggressive behavior to defend their turf and woo females. Non-territorial males are similar to females, lacking the behavior of courting females, and their reproductive organs have degenerated due to the influence of hormones.
Hormonal influencesThese shifts in social roles can lead to changes in the brain and reproductive system, and the shift in social identity not only affects behavior but also changes their physiological state.
According to several studies, the stress hormone cortisol plays a major role in shifting social status. When faced with chronic stress, male fish experience reproductive suppression as the body prioritizes coping with the stressor rather than directing metabolic energy toward long-term reproductive goals. Territorial and nonterritorial males differ significantly in plasma concentrations of testosterone and 11-ketotestosterone, and changes in these hormones are closely related to their social phenotypes.
Territorial males showed significantly higher levels of these androgen levels, while non-territorial males showed the opposite.
Female influence
The social role changes of males are also influenced by the females around them. Female fish can transition between different social environments depending on their reproductive status, a process that is tied to the females around them. Studies have found that females have multiple mating preferences that change as their reproductive state changes. When females are carrying eggs, they prefer to be with territorial males, but when they are without eggs, they have no obvious preference.
Reproductive behavior
Male courtship and oral behavior
Astatotilapia burtoni is a performative species, and territorial males display to attract females. Research shows that the color of a male fish's dorsal fin is crucial to attracting females. Males display their bodies sideways and shake their bodies to attract the attention of females, and release pheromones to stimulate female ovulation.
Once the female is ready to lay eggs, the male guides her to the egg-laying site and repeats the act of insemination.
Mother's oral care
After laying eggs, the female collects them in her mouth and broods them, a behavior called mouth-brooding. Experience shows that too much noise can have a negative impact on oral breeding behavior, causing females to be unable to safely protect their cubs and even to cannibalize their eggs.
Communication
Sound signal
Most animals utilize multimodal communication, and Astatotilapia burtoni is particularly good at this. The courtship process of these fishes relies not only on visual signals, but also on the transmission of sound signals. Studies have shown that territorial males make specific calls to attract females, and the characteristics of these calls are linked to their body movements.
The sounds males make are not only intended to attract females, but are also closely tied to their reproductive cycles and may be affected by hormone levels.
In an environment of underwater noise, males' courtship behavior and the way they produce sounds are also affected, and such changes may reduce females' perception of male voices. The behavior of these fish not only reflects the complexity of social structure, but also reveals how hormones play a decisive role in this process.
The behavior of Astatotilapia burtoni and the role of hormones in its social status make us rethink how social animals respond to changing environments and social structures, and what can we learn from these creatures?
