83 Adaptations and Fitness

Key Idea: An adaptation is any heritable trait that equips an organism for its functional role in the environment (its niche). An adaptation is any heritable characteristic (trait) that equips an organism for its niche, enhancing its exploitation of the environment and contributing to its survival and successful reproduction (fitness). The adaptations that evolve in species are the result of the selection pressures to which they are exposed throughout the course of their evolution. Traits that are not helpful to survival and reproduction will not be favoured and will be lost. Adaptations may be structural (morphological), physiological, or behavioural. The speciation of two New Zealand parrots, the kea and kaka, from a common ancestor illustrates the importance of adaptation to a particular habitat and niche.

Kea are inquisitive and highly intelligent. They have been filmed using tools and are adept at problem solving. Name: Kea (Nestor notabilis)

Habitat

` Alpine (mountain) regions in the South Island.

Structural adaptations

` Dense plumage provides insulation against the cold. ` Robust body for surviving in the cold. ` Large, narrow curved beak and claws for manipulating foods, and to move and investigate objects.

Physiological adaptations

` Excellent vision and can identify and process a wide variety of foods, including plants, insect larvae, birds, carrion, mammals (including sheep), and human scraps.

Behavioural adaptations

` Highly social, intelligent, and curious (characteristics useful in investigating and exploiting new food sources).

Proto-kaka

The kea and kaka diverged from a common proto-kaka ancestor about 3 mya. The rise of the Southern Alps provided a new alpine habitat that the ancestral kea occupied. The kaka ancestor remained in forested areas.

Kaka uses its claws and beak to manipulate food and climb through the branches.

1. What is adaptation?

2. What event resulted in the kea and the kaka diverging and what was its effect?

3. Describe how the adaptations of kea and kaka help them exploit the foods available in two very different environments:

Rosino cc 2.0

Matt Binns cc 2.0 Name: Kaka (Nestor meridionalis)

Habitat

` Forest-dwelling, found throughout New Zealand in localised forest strongholds. More arboreal than kea.

Structural adaptations

` A brush tongue to remove nectar from flowers. ` Strong, broad beak used for tree climbing, digging out insects, and opening kauri cones to obtain the seeds. ` Strong, agile feet are used to hold food and to cling onto branches while feeding. ` Strong fliers, can weave between trees.

Physiological adaptations

` Excellent vision and can identify and process a wide range of foods including seeds, fruits and berries, flowers, buds, nectar, honeydew, and invertebrates. ` Produce a second clutch in a season if food is abundant.

Behavioural adaptations

` Seasonal specialists, exploiting different food sources as they become available. ` Will congregate at abundant food sources or forage alone.