Parasitism and developmental plasticity in Alpine swift nestlings

Area of Science:

• * Evolutionary biology
• * Phenotypic plasticity
• * Host-parasite interactions

Background:

• * Development plasticity is a key evolutionary response to environmental stress, particularly in species with determinate growth.
• * Organisms adjust the plasticity of different body structures based on their contribution to fitness.
• * Parasite infections can impact offspring development, potentially triggering compensatory growth mechanisms.

Purpose of the Study:

• * To investigate if host nestlings can compensate for parasite effects on development.
• * To test the accelerated growth and delayed maturation hypotheses in response to fluctuating parasite loads.
• * To experimentally manipulate parasite load in Alpine swifts (Apus melba) and observe developmental plasticity.

Main Methods:

• * Experimental increase and decrease of louse-fly (Crataerina melbae) load in Alpine swift nests.
• * Monitoring parasite intensity and nestling growth (body mass, wing length) throughout the rearing period.
• * Analyzing growth rates before and after peak parasite infestation.

Main Results:

• * Parasitized nestlings exhibited slower wing growth before peak infestation and faster growth after.
• * Wing growth duration was extended by 3 days in parasitized nestlings.
• * Body mass growth was not significantly affected by parasite load.
• * Wing size at fledging was similar between parasitized and deparasitized nestlings.

Conclusions:

• * Alpine swift nestlings demonstrate developmental plasticity to compensate for parasite-induced stress.
• * The accelerated growth and delayed maturation hypotheses provide valid explanations for observed compensation.
• * Understanding parasite population dynamics is crucial for studying host-parasite relationships and host development.