The Diversity of Living Things An Introduction. How many species exist on Earth?. Estimated = 8.7 million. Actual number identified by scientists = 2 million. Species – a group of organisms that can interbreed in nature & produce fertile offspring. How do scientists identify a species?.
Estimated = 8.7 million
Actual number identified by scientists = 2 million
Species – a group of organisms that can interbreed in nature & produce fertile offspring.
- Structural features (body shape, size, etc.)
- Whether or not two organisms can produce fertile offspring
- Evolutionary history of a species
Many organisms have been given several names that differ from place to place.
Scientific Name: Marmotamonax
Taxonomy – a branch of biology that identifies, names, & classifies species.
Binomial Nomenclature – a system of giving a two-word Latin name to each species
Aka “grey wolf
Genus – a taxanomic group of closely related species
Species are arranged in categories from most general to most specific.
Taxon – a named group of organisms
To begin the key, you could start separating the four insects based on wing covering "wings covered by exoskeleton" vs. "wings not covered by exoskeleton."
b. wings not covered by exoskeleton….go to step 3
Step 2. a. body has a round shape .………………..ladybug
b. body has an elongated shape .…….…grasshopper
Step 3. a. wings point out from side of body …dragonfly
b. wings point to posterior of body.……housefly
Notice that there were four organisms to be identified and it only took three steps. Usually, there should be one less step than the total number of organisms to be identified in your dichotomous key.