Population Changes and Natural Selection

Biodiversity Biodiversity, or biological diversity, is the sum of an area’s organisms, considering the diversity of species, their genes, their populations, and their communities. A species is a particular type of organism; a population or group of populations whose members share certain characteristics and can freely breed with one another and produce fertile offspring.

Biodiversity Costa Rica’s Monteverde Cloud Forest is home to many species and possesses great biodiversity. Figure 5.1

Abiotic Factors Biotic Factors All of the living organisms within an ecosystem Examples: Plants Animals Fungi Any other living things All of the non-living things in an ecosystem Directly affect how organisms survive Examples: Amount of Water Temperature Acidity of Water Weather Natural Disasters

Limiting factors Environmental factors that limit population sizes in a particular environment Examples: Food Water Predators Temperature

How Population Changes Happen Charles Darwin Developed the theory of evolution Different birds had different beaks – They each adapted to a different island environment. Speciation Formation of a new species as a result of change over time

Natural Selection The process by which individuals that are better adapted to their environment survive and reproduce Individuals who do NOT adapt are less likely to survive and reproduce

Natural selection Fitness = the likelihood that an individual will reproduce and/or the number of offspring an individual produces over its lifetime Adaptive trait, or adaptation = a trait that increases an individual’s fitness

Natural selection Evidence of natural selection is all around us: In nature … Diverse bills have evolved among species of Hawaiian honeycreepers. Figure 4.23a

Beak Types Resulting From Natural Selection Unknown finch ancestor Insect and nectar eaters Fruit and seed eaters Greater Koa-finch Kona Grosbeak Akiapolaau Maui Parrotbill Kuai Akialoa Amakihi Crested Honeycreeper Apapane Beak Types Resulting From Natural Selection

Natural selection Evidence of natural selection is all around us: … and in our domesticated organisms. Dog breeds, types of cattle, improved crop plants—all result from artificial selection (natural selection conducted by human breeders). Figure 4.23b

4 Steps of Natural Selection Overproduction Inherited variation Struggle to survive Successful reproduction

It’s been said that every person on the planet, around 6,2 billion of us, could fit into the state of Texas. How would life be if everyone lived in TX? Describe what you believe it would be like. Explain. Cougar Hunt