Transcript document

Welcome to Organismal Biology
BIOL 1030
Dr. Boyd
What’s a species?
• Species: “Kind of living thing”
• Word “species” is both plural and singular
• Biological species concept: Group of similar
individuals capable of interbreeding to produce fertile
offspring
– Problems: What about species that reproduce
asexually? What about extinct species?.
What’s a species?
• Species: “Kind of living thing”
• Word “species” is both plural and singular
• Biological species concept: Group of similar
individuals capable of interbreeding to produce fertile
offspring
• Evolutionary species concept: Line of descent
(lineage) that maintains its distinctive identity from
other lineages.
Naming Species
• Binomial system: Each species’ official scientific
name is made of 2 words
• Bi=“2” nomen=“name”
• First is “genus”
• Second is “specific name”
• Together these make up a species’ scientific name.
Naming Species
• Example: Our species
• Homo sapiens
• Written in italics to show it’s not an English word: it’s
Latin
• Often name means something
• Homo sapiens means “wise human” or “wise being”.
Naming Species
• Sometimes species named after person
• Someone famous among scientists, a far-thinking,
brilliant, innovative scientist.
Naming Species
• Example, Melanotrichus boydi
• Insect found only on plant in
California that takes lots of Nickel
into its tissues.
Plant:
Streptanthus
polygaloides
Species: How many are there?
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Answer: Nobody knows!
1.5 million named and described
Guesses suggest 10 million may exist!
Human activities are destroying many before they are
discovered by science.
Clear-cutting in
Malaysian rain forest
Classifying Species
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Classification: Grouping species into larger units
Species into Genus
Genera (plural of genus) into Family
Families into Order
Orders into Class
Classes into Phylum
Phyla (plural of phylum) into Kingdoms
Kingdoms into Domains.
Classifying Species
• Example for the eastern gray squirrel, Sciurus carolinensis.
Fig.
32.4
Hierarchical: smaller groups nest within larger ones.
Classification Approaches
• Phylogeny: Explanation of evolutionary
relationships among groups
• Phylogram: Diagram that shows a phylogeny.
Fig.
32.11
Classification Approaches
• Groups of organisms may be:
– monophyletic (includes most recent common ancestor and
all descendants)
– paraphyletic (includes most recent common ancestor BUT
not all descendants)
– polyphyletic (does not include most recent common
ancestor).
Fig. 32.6
Classification Approaches
Often, biologists prefer monophyletic groups.
Classification Approaches
• Systematics: The study and reconstruction of
phylogenies
• Two major approaches:
– cladistics
– traditional taxonomy.
Classification Approaches:
Cladistics
• Groups organisms on basis of unique shared
characters inherited from common ancestor
• Clade: group of organisms related by descent
• Cladogram: phylogram based on cladistic analysis.
Fig. 32.7
Classification Approaches:
Cladistics
• phylogram based on cladistic
analysis
Shared
derived
characters
define each
branch.
Fig. 32.7
Classification Approaches:
Cladistics
• phylogram based on cladistic
analysis
Lamprey is
outgroup: organism
not a member of
rest of clade that
serves as point of
comparison
Other organisms
are ingroups (here
animals with jaws).
Classification Approaches:
Traditional Taxonomy
• Considers:
– 1) lines of descent
– 2) evolutionary importance of characteristics (gives
“weights” to characteristics).
• May give different classification than cladistic
approach
• Example, classifying birds.
Classification Approaches:
Traditional Taxonomy
Fig.
32.8
Traditional taxonomists view importance of feathers as being
so great that birds are placed in own Class (thus Reptilia is paraphyletic
here). Cladists put birds with reptiles to make Reptilia monophyletic.
Characters Useful for Classification
Morphology
Nutrition mode
Cell structure
Chemistry
Reproductive traits
Many others
Characters Useful for Classification
Morphology
Form of organism
Development (IF body develops: unicellular vs.
multicellular life)
Presence or absence of various structures
Nutrition mode
Cell structure
Chemistry
Reproductive traits
Many others
Characters Useful for Classification
Morphology
Nutrition mode
Autotroph (photosynthetic)
Heterotroph (consumes other living things or their
products)
Cell structure
Chemistry
Reproductive traits
Many others
Characters Useful for Classification
Morphology
Nutrition mode
Cell structure
Presence/absence of nucleus, other organelles
Presence/absence of cell wall
Presence/absence of flagellae
Etc.!
Chemistry
Reproductive traits
Many others
Characters Useful for Classification
Morphology
Nutrition mode
Cell structure
Chemistry
Cell wall make-up
Energy storage materials
Photosynthetic pigments
DNA/RNA/protein sequences
Reproductive traits
Many others
Characters Useful for Classification
Morphology
Nutrition mode
Cell structure
Chemistry
Reproductive traits
Asexual reproduction (by mitosis): Produces genetically
identical offspring
Sexual reproduction: Produces genetically different
offspring
Many others
Focus on Life Cycles
Always involve:
Meiosis (reduction division): diploid (2N) cell produces
one or more haploid (1N) cells. Chromosome number
halved
Gametes: Cells that must join to another cell before a new
organism is produced
Fertilization (syngamy): Forms zygote, first diploid cell.
Focus on Life Cycles
Always involve:
Meiosis (reduction division): diploid (2N) cell produces
one or more haploid (1N) cells. Chromosome number
halved
Gametes: Cells that must join to another cell before a new
organism is produced
Fertilization (syngamy): Forms zygote, first diploid cell
May involve:
Meiospore: Cell made by meiosis that can grow into new
organism by mitosis, without joining with another cell.
Major Life Cycle Types
Meiosis makes gametes
Organism spends most of
life in diploid phase
(diploid dominant)
Gamete is ONLY haploid
cell (hence “gametic
meiosis”).
Fig. 32.14b
Major Life Cycle Types
Meiosis makes meiospores,
which grow are (or grow
into) haploid individuals
Organism spends most of
life in haploid phase
(haploid dominant)
Zygote is ONLY diploid
cell (hence “zygotic
meiosis”).
Fig. 32.14a
Major Life Cycle Types
Meiosis makes meiospores,
which grow grow into
haploid individuals
(called gametophytes)
Gametophytes make
gametes BY MITOSIS
Zygote grows into diploid
individual called
sporophyte
Sporophyte makes
meiospores BY MEIOSIS
Two bodies in one cycle:
alternation of generations.
Fig. 32.14c
Characters Useful for Classification
Morphology
Nutrition mode
Cell structure
Chemistry
Reproductive traits
Many others
Domains/Kingdoms of Life
Bacteria separated
from rest is either
two domains or
two kingdoms
Bacteria are
prokaryotes (lack
membrane bound
organelles)
Rest of life as 4
kingdoms
1030 covers Eukarya.
We will be here!
Domain Archaea (Archaebacteria)
Prokaryotes (review BIOL 1020 notes)
Poorly known
Many have special habitat needs:
Methanogens: Cannot survive in oxygen (anaerobes).
Obtain energy by reducing CO2 using H2 to make
methane CH4.
Extremophiles:
Thermophiles: Live at 60-113C.
Domain Archaea (Archaebacteria)
Nevada hot spring inhabited by Thermophiles.
Domain Archaea (Archaebacteria)
Prokaryotes
Poorly known (100 species known?)
Many have special habitat needs:
Methanogens: Cannot survive in oxygen (anaerobes).
Obtain energy by reducing CO2 using H2 to make
methane CH4.
Extremophiles:
Thermophiles: Live at 60-113C
Halophiles: Live at high salinities
pH-tolerants: Very acid (0.7) or very alkaline (11)
Pressure-tolerants: Some can survive 800
atmospheres!.
Domain Bacteria (Eubacteria)
Prokaryotes
Systematics poorly known (2600 species known?)
More discovered constantly.
Finding new bacteria
• Deep crust/deep
sediment bacteria
• Discovered in 1990s
• Up to 6.5 km deep in
sediments
• Up to 2.8 km deep in
crust
Finding new bacteria
• Example:
• Bacillus infernus
– The “Bacillus from Hell”
– 2,800 m deep in Virginia
B. infernus
Domain Bacteria (Eubacteria)
Prokaryotes
Systematics poorly known
Abundant:
1) more in your mouth than mammals on Earth!
2) 5 million per square cm of your skin
3) 1 gram of soil has 2.5 billion bacteria
4) more biomass than rest of life on Earth combined!
Domain Bacteria (Eubacteria)
Play important roles in life:
1) Some are photosynthetic (vital for putting energy into
ecosystems)
2) Some are decomposers (vital for recycling matter in
ecosystems)
3) Some cause disease.
Domain Eukarya
Eukaryotes (review BIOL 1020 notes)
Differ from other domains by:
1) multicellularity: body formed of cells which are in
contact and coordinate activities
Note some eukaryotes are unicellular or colonial
(aggregation of cells with little coordination of activities)
2) sexual reproduction: absent from all bacteria known
Note some eukaryote groups rarely or never reproduce
sexually (only asexual reproduction has been observed)
But, evolution of eukaryotes involved endosymbiosis,
incorporation of Eubacteria cells into eukaryotes as
mitochondria and chloroplasts.
Domain Eukarya
The mitochondria of all eukaryotes, and the chloroplasts of
photosynthetic ones, evolved from Eubacteria.
Domain Eukarya
The mitochondria of all eukaryotes, and the chloroplasts of
photosynthetic ones, evolved from Eubacteria.