Ecological Fitness Amphibians, Reptiles, and Birds

Ecological Fitness How well an organism has adaptations well suited to its environment An ecologically fit organism has a survival advantage

Adaptation An inherited characteristic that increases an organisms ability to survive an environmental change Examples: ability to grow a winter coat Important concept: an organism cannot acquire an adaptation during its lifetime An adaptation is coded into an organisms DNA and cannot be changed

The migration onto land The first vertebrates were fish Water is a nice environment There is no weather, water temperature is fairly stable, no need to maintain body temperature No issue with drying out No need to protect reproductive cells, egg and sperm No need to protect embryo

Thermoregulation Life on land requires adaptation to the wide swings in ambient temperature Ectothermy: the body temperature of the organism is the same as its environment Endothermy: the organism maintains a constant body temperature

Amphibians Live part of their life in the water, usually a juvenile stage Have gills while in the water Live on land as adults Have lungs or not All absorb oxygen from the air through their skin Require that their skin stays moist, mucus

Amphibians continued 3 chambered heart, oxygen rich blood and oxygen poor blood mix Many lay their eggs in the water Cloaca used for excretion and reproduction Examples: salamanders, frogs and toads Ectothermic Must hibernate during the winter

3 chambered heart

Cloaca

Reptiles Permanent land residents Must have adaptations against drying out, scales Eggs must have some protection, leathery shell Ectothermic 3 chambered heart, usually Cloaca for excretion and reproduction

Reptiles continued Cannot live in cold climates In temperate zones, reptiles hibernate for the winter, usually underground

Birds Related to bird hipped dinosaurs such as T rex Endothermic, so can live in cold environments Eat a variety of items that are available during the winter or migrate Brood their young, eggs have hard shells allowing mother to sit on eggs Involved parents allows more survival from less eggs

Birds and Flight 4 chambered heart Light bones Feathers One way air flow through lungs Flying expands available food sources and decreases predation

Bird Respiratory System