Download File

Ch. 18
Part 1
Species
• A group of organisms with similar morphology and
physiology, which can breed together to produce
fertile offspring that are reproductively isolated
from other species
– 1.5 million animal species
– 250,000 flowering plant species
– Exact number of different spies (including ALL 3
domains of life) unknown
• Places that have remained unexplored
• Disagreements on divisions of species among scientists
• Estimates range up to 100 million
• Binomial Nomenclature
–
–
–
–
2-name naming system
Carolus Linnaeus, 18th century
Name a species using Genus and species
Examples:
•
•
•
•
Homo sapiens (H. sapiens)
Pantera leo (P. leo)
Canius lupus (C. lupus)
Canius domestitcus (C. domesticus)
Ecosystem
•
•
Relatively self-contained, interacting community •
of organisms and the environment they live in
and in which they interact
•
Includes biotic and abiotic factors
–
–
Biotic  living factors/interactions
Abiotic  non-living factors
•
•
•
•
•
Soil
Leaf litter
Humidity
Temperature
Different scales or levels
–
–
Simple desert
Complex  tropical rainforest
Habitat
Place where an organism lives
within an ecosystem
Niche
– The role an organism plays in an
ecosystem
– More than a physical description of a
place
– How the organism “fits” into
ecosystem
• Describes:
– Where organism is in ecosystem
– How it obtains energy
– How it interacts with physical
environment
– How it interacts with other
species
– Niche for large, herbivorous animals
• Australia vs. Africa
– Different species can occupy
similar niches because they feed
off of different vegetation
– Impossible to completely
describe a niche because there
are so many ways in which one
organism can interact with the
other components of the
ecosystem which it is part of
Diversity
• “catalogue of different species”
• Rich in different species
• Most biodiverse ecosystems
– Tropical forests
– Coral reefs
• Biodiversity
– Degree of variation of life forms
in an ecosystem
– Three levels:
1. The variation in ecosystems or
habitats (Ecosystem Diversity)
2. The number of different species
in an ecosystem and their relative
abundance (Species Diversity )
3. The genetic variation within each
species (Genetic Diversity)
•
•
•
Species Diversity
A measure of species richness in a community and the evenness of the abundance of the different
species
The more species AND the more evenly the number of organisms are distributed among different
species = increased species diversity
Ecosystems with high species diversity = more stability than ecosystems with limited diversity
–
•
Ecosystems with less extreme conditions = more species diversity
–
•
More resistant to changes
Tropics vs. the tundra/desert
Ecosystems dominated by one or two species are rare
–
–
Pine forests in Florida
Temperate forests in Canada
•
Genetic
Diversity
Provides populations with the ability to adapt to changes in biotic and abiotic
factors
• Definition:
– Diversity of alleles within the genes in the genome of a single species
• All individuals of species have the same genes but NOT necessarily the same alleles
• Assessed by determining what proportion of genes have different alleles and how
many alleles per gene
• Genetic differences between populations of same species due to adaptations in
different ranges
– Geographic Range: location in which that species is distributed
• boundary beyond which a species does not occur, the limit or limits of the range of a species
– Important for adaptation to environment (biotic and abiotic factors)
Assessing Species Diversity
• To determine species
diversity:
– Observation skills important
– Identify and catalogue types
of organisms in an
ecosystem
– Build a species list
– Use identification keys to
name the species collected
• Drawings/photos with IDs
• Question maps
• Dichotomous keys
– Used to identify and
differentiate between a
variety of species
Dichotomous Key
Collecting and Identifying Species
• Timed search in area to
collect and ID as many
species as possible
• Unable to ID = take pics
and label species A, B,
C, etc.
– Use pics with reference
materials to ID later on
• Hard to collect species
– Use special collection
tools
• “pooter”
– Use magnifying
glass/hand lens to
analyze more closely
and ID