Adaptation

What is adaptation? Any trait that enhances an organism’s fitness or that increases its chance of survival and probability of successful reproduction

It is always a struggle for plants and animals to survive ANIMALS STRUGGLE : For food For water For protection against weather Against being eaten by predators Against disease Against accidents PLANTS STRUGGLE: For water For light For minerals in the soil Against weather Against disease Against being eaten

How does adaptation help organisms? Well adapted organisms are better at coping with extremes of weather They are better at competing for food They are better at escaping from predators They are more likely to survive in their habitat and produce offspring

How do adaptations arise? Organisms become adapted to their immediate environment over a period of time through natural selection The genetic characteristic that are best adapted to the environment are selected

Evolution of Complex Adaptations complex adaptations such as the change from a simple to a complex eye evolve over time as a result of a series of small adaptive changes the adaptations in the organisms living today are the result of natural selection acting on chance variations that arose at particular times in history

Types of Adaptations structural (anatomical) physiological behavioural

Structural shape or arrangement of particular features ex. Arrangement of teeth, shape of fins or beaks  mimicry which allows one species to resemble another species. Cryptic colouration makes potential prey difficult to spot Ex sea horse called a sea dragon looks like the algae in which it lives  Internal: ex strong muscle walls of human heart, long digestive tract of herbivores

Classification of Structures Homologous structures - similarity in structure due to common descent, not reliant on function. E.g. vertebrate forearms: human hand, bat wing, whale fin, cat leg. Analogous structures - similarity in structure based on adaptation for the same function, not common descent. E.g. wings have developed independently in insects, reptiles, birds, and bats.

Homologous Structures All have the same bones, but are used in different ways and for various functions - remember, homologous structures have common ancestry!

Homologous Structures

Analogous Structures Wings of bat, bird, and insect have the same function, but are not from the same descent

Comparison Between Homology and Analogy

Comparison cont.

Vestigial Structures Is a structure that appears to have lost its functionality. If organisms were created "de novo," why do they retain these vestiges? The eye bulbs of blind, cave-dwelling creatures, such as the grotto salamander (Typhlotriton spelaeus).  

Structural Adaptation: A Special Case, Mimicry Mimicry is one of several anti-predatory devices found in nature. Specifically it is a situation in which one species called the mimic resembles in color, form, and/or behavior another species called the model. In so doing, the mimic acquires some survival advantage.

There are 2 basic forms of mimicry 1. Batesian - the mimic (palatable) resembles the model (unpalatable) and only the mimic benefits. 2. Mullerian - both the mimic and the model are unpalatable and both benefit.

Physiological Adaptations associated with functions in organisms Ex enzymes for blood clotting, chemical defenses of plants

Behavioural Adaptations associated with how organisms respond to their environments Ex: migrations, courtship, foraging behaviour, response of plants towards light