Evolution and Biodiversity. Chapter 3 Pages 46-62. Evolution: All species descended from earlier ancestral species. Changing genetic make- up in a population over time. Accepted scientific explanation of how animals adapt and survive. Evolution and Adaptation.
descended from earlier
Changing genetic make-
up in a population over
explanation of how
animals adapt and
Macroevolution – long term, large scale changes
Microevolution – small genetic changes
Gene pool – all genes in a population
Mutation – random change in structure of DNA. Every so often, a mutation is beneficial for survival.
Natural selection – individuals that have traits that benefit survival.
Microevolution is changes in the gene pool of a population over time that result in changes to the varieties of individuals in a population such as a change in a species' coloring or size.
Macroevolution If the changes are over a very long time and are large enough that the population is no longer able to breed with other populations of the original species, it is considered a different species.
Three things must happen:
1. Genetic variability in a trait within population
2. Trait is heritable
3. Differential reproduction – must enable individuals with the trait to leave more offspring than others without the trait.
Adaptive (heritable) trait helps survival and reproduction under current conditions
Ecological niche – role in ecosystem. Includes interaction with biotic and abiotic factors.
Habitat – physical location
In other words:
Niche – species occupation
Habitat - address
species to coexist. This is biodiversity.
What is better? Depends…
Environmental conditions consistent – favors specialists. Fewer competitors, food plentiful
Rapidly changing environmental conditions – favors generalists… More adaptable.
Fig. 5-7 p. 94
Changes in Earth’s biodiversity – has leveled off during the last 1.8 million
Years. Is this due to human influence?
Adaptive radiation – after mass extinctions, numerous new species evolve to fill vacated niches. Takes 1-10 million years for adaptive radiation to rebuild biodiversity.
Human impacts – accelerated extinction
Artificial Selection – artificially selecting superior genetic traits
Species creation in laboratories
Takes less time than artificial selection
Concerns about Genetic Engineering
Many failures (1% success rate)
Lead to more abortions? Only for the wealthy?
major vegetation types on land – based on different climates and atmospheric conditions
forests, grasslands, deserts
tropical, temperate, polar
temperature and precipitation determine overall patterns
What biome do we live in?
Biomes across 39th parallel
The two most important factors influencing vegetation in the
formation of biomes are precipitation and temperature.
majority of marine species (90%)
most commercial fisheries and interaction with land and humans
90% of ocean area
where rivers meet ocean
Coral reefs and mangrove forests