The ecosystem is a biological community of interacting organisms and their physical environment. Species are the basic unit of biological classification and a taxonomic rank. Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species.
There are over 8 million species on earth, but only 1.9 million species have been named.
Species richness is the number of species in an ecosystem and doesn't take in to account the abundance of the species. Species evenness is how close the number of species in an ecosystem are. An area with a high richness and a low evenness is
Phylogenies are the changes in a species or group over a period of time compared to the development of an individual. A phylogenetic tree shows the changes in a species overtime.
In this section we learned about the different ways evolution can occur.
Micro evolution is the changes in a small group of species after a short period of time. An example of this is when a bacteria evolves when a antibiotic is used to kill it. Macro evolution is the change in a large group of species over a long period of time. An example of this is when a species splits into two groups of species over a long period of time.
Difference between macro and micro evolution
Mutations can be caused by DNA not properly copying, or they can occur from an external influence like UV rays. If a mutation occurs it can be passed down to the offspring and they can pass it down and slowly change the species.
A genotype is the complete set of genes in an individual. An example of a genotype is the alleles in an individual. Phenotype is the physical traits in an individual. An example of this is eye color. Phenotype are almost only determined by an organisms genes.
Evolution by artificial selection is when humans determine which individuals to breed. An example of this is when we bred wolves and chose which to breed and through this we ended up with different types of dogs.
Wolves artificial selection to dogs
Evolution by natural selection is when the environment determines which individuals will survive and pass on their genes and which will die. An example of this is if the environment is more cold, species that have adapted to the cold will survive while the other will die off. Darwin had 5 key ideas about this theory.
Fitness is used to describe a genotype that is more desired than another genotype. For example rabbits with white fur in the arctic are more desired because they blend in with the snow and are harder for predators to hunt them. Adaptation is the change in a species that makes them better suited for there environment. The difference between the two is fitness is being able to survive in an environment and adaptation is when a species changes to survive in an environment.
Evolution can occur in many different ways. Some of the ways it can occur is through mutations, genetic drift, bottleneck effect, and founder effect.
In this section we learned about environmental change can affect speciation and extinction.
Geographic isolation is when a population of a species cant exchange their genetic material due to geographic problems. One example of this is are physical barriers like a body of water or a large mountain splitting up a group of species.
Example of geographic isolation
Reproductive isolation is when some properties of an individual prevents it from interbreeding. This could be due to different mating times, mating rituals, and mating location.
Allopatric speciation is the process of speciation that occurs with geographic isolation. It occurs when a population is split by a physical barrier and they split into two populations.
Sympatric speciation is the evolution of one species into two, without geographic isolation. Some species will become polyploidy and can no long interbreed with diploid organisms.
The pace at which evolution occurs at depends on several factors. Environmental change can cause evolution to occur quicker than usual. The faster the environment changes, the faster species have to evolve survive in there environment. Other things that can affect evolution is genetic variation, population size, and generation time. Slow rates of evolution can be caused by longer generation times, or when a population has a low genetic variation.
Genetically modified organisms or GMO's are the result of a laboratory process where genes from the DNA of a species are extracted and put into the genes of another species. GMO's are mainly used in our food and too crops. When added to crops it can cause them to have herbicide tolerances and it can cause them to gain the ability to produce its own pesticide. One of the largest food that contains GMO's is corn. Almost 85% of corn grown in the U.S. is genetically modified. The corn that is modified is modified so it is resistant to herbicide glyphosate, which is used to kill weeds.
A fundamental niche is the suite of abiotic conditions under which species can survive, grow, and reproduce. A realized niche is the range of both abiotic and biotic conditions under which a species actually lives.
A generalist is a species that can survive under a large range of conditions, while a specialist is a species that is specialized to live under specific conditions .
Environmental change has altered tree species distribution overtime. 12,000 years ago as the glaciers started to recede and trees started to move further and further north.
There are many ways a species can go extinct, but there are three of the biggest reasons they go extinct is because of climate change, diseases, and humans. Humans are the biggest reasons species have gone extinct in the past 60,000 years. Humans have destroyed habitats and have caused the rate at which climate change occurs to increase.
The Golden frog is one animal that has gone extinct
Mass extinctions have occurred 5 times on earth. A mass extinction is a rapid decrease in biodiversity on earth. About 65.5 million years ago scientists believed that climate change occurred that interrupted the food supply for dinosaurs, but in the 1980's two scientists found a layer of iridium. Iridium is an element found only in space, and it corresponded to the time the dinosaurs died off. Scientists believe now that an asteroid or a comet crashed into earth and killed the dinosaurs.
We are currently in a time period of a mass extinction. It is different from other mass extinctions however because all extinctions that occurred before humans were around were caused by meteors or the environment changing, but now this mass extinction is caused by humans destroying habitats and climate change.
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