A characteristic that helps an organism SURVIVE and REPRODUCE in its environment
What are 3 examples of adaptations ?
1. an organism can change its form or behavior so it can find food
2. an organism can change its form or behavior so it can protect itself
3. an organism will move from place to place
A group of organisms that can mate with one another to produce fertile offspring.
A species is the most specific of the seven levels of classification!
What does fossil evidence show?
that living things have changed over time - since life first appeared on Earth, many species have died out and have been replaced by newer species.
the process by which populations accumulate inherited changes over time
What are the 3 types of evolutionary evidence?
2. Vestigial Structures
3. Comparing Organisms
the solidified remains (imprints) of once-living organisms that are found in the layers of the Earth
The 'fossil record' is
a historical sequence of life indicated by the fossils found in the layers of the earth's crust
Fossils found in the upper crust (new layer) resemble what?
These fossils tend to resemble present-day organisms. So this indicates that these fossilized organisms were close relatives of present-day organisms
Fossils found in the deeper layers of the earth resemble what?
These fossils look less like present-day organisms
Gaps in the fossil record exist because ...
Specific conditions are necessary for fossils to form -
What conditions are necessary for fossils to form?
the organism must be buried in a fine sediment and oxygen can't be present (because oxygen causes decay). Since oxygen occurs nearly everywhere, fossils can't form.
Define 'Vestigial Structures'
these are remnants of once useful structures in an organism (in an earlier evolutionary form, that structure helped the organism, but as the organism evolved it no longer needed that structure but for some odd reason it still remained)
Describe how scientists compare skeletal structures ... Why do scientists do this?
When you look at the structure and order of the bones found in limbs across organisms (human arm v. cat's leg), you see they are actually very similar to one another
THIS INDICATES THAT ANIMALS/ORGANISMS THAT APPEAR SO DIFFERENT ARE ACTUALLY ALL RELATED BY A COMMON ANCESTOR
Describe how scientists compare DNA from species ... Why do scientists do this?
Scientists hypothesize that if all organisms living today evolved from a common ancestor, they should all have the same kind of genetic material - they do! They all have DNA!
And those species that appear to be close relatives should have greater similarities in their DNA than species appearing to be distant relatives
Describe how scientists compare embryonic structures ... why do scientists do this?
Early in development, human embryos of all other vertebrates (have a backbone) look similar because we share a common ancestor.
But embryo development has evolved over millions of years causing the embryonic structures to grow into MANY different species of vertebrates