Evolution of morphological integration: developmental accommodation of stress-induced variation

Area of Science:

• Evolutionary biology
• Developmental biology
• Ecology

Background:

• Extreme environmental changes can induce developmental abnormalities in organisms.
• The evolutionary impact of stress-induced variation depends on stressor recurrence and the organism's ability to accommodate errors.
• Understanding how organisms cope with developmental stress is crucial for evolutionary adaptation.

Purpose of the Study:

• To investigate the effects of extreme environmental conditions on morphological integration and developmental error accommodation in soricid shrews.
• To analyze how functionally integrated traits respond to developmental stress compared to other traits.
• To explore the link between individual adaptation to stress and the evolution of stress resistance.

Main Methods:

• Subjecting four species of soricid shrews to an extreme environment during growth.
• Measuring changes in morphological variation and integration within mandibular traits.
• Comparing individuals grown under extreme conditions to those grown under control conditions.

Main Results:

• Adult shrews grown in extreme environments exhibited reduced integration and increased fluctuating asymmetry in mandibular traits.
• Functionally integrated traits (within muscle attachments) showed less response to stress and maintained integration better than other traits.
• Cohesiveness in functionally integrated trait complexes was preserved through covariation of developmental variation under stress.

Conclusions:

• Developmental accommodation of stress-induced variation allows individuals to function and persist under extreme conditions.
• This accommodation provides a mechanism linking individual adaptation to environmental stress with the evolution of stress resistance.
• The study highlights the importance of functionally integrated traits in buffering against developmental abnormalities caused by environmental stressors.