classifiaction and phylogeny 1-11-05bsc2011l/sp_05_doc/classifiaction_and... · monera protista...
TRANSCRIPT
Announcements:
1. Labs meet this week
2. Lab manuals have been ordered
3. Some slides from each lecture will be on the web
4. Study questions will be posted after each lecture
Monera AnimaliaFungiPlantaeProtista
Prokaryotes Eukaryotes
MetazoaProtozoa
HeterotrophicAutotrophic
Absorptive Ingest/digest
What is an Animal ?
1. Animals are multicellular, heterotrophic, eukaryotes that ingest and digest their food.
2. Animals lack a cell wall.
3. Are capable of moving (during some point in their lives).
4. All animals have regulatory genes called Hox genes.
•To date > 1.5 million species of animals have been described by biologists
• ~ 10, 000 new species are described each year
•Estimates of the total number of animal species are around 10 million.
What is a Species?
Species Concepts:
1. Typological species concept: species are distinct, unchanging entities defined by unique, morphological features. This concept has been abandoned by biologists.
It ignores evolution: species are not “unchanging entities”
Some Problems with the Typological Species Concept
1. Artificial selection: artificial selection for oil content in corn
High oil
Low oil
Natural selection: Trinidadian guppies
Sexual Dimorphism: the sexes differ morphologically
Some Problems with the Typological Species Concept
Sailfin molly
femalemale
Alternative morphs:
e.g. horn polymorphisms in beetles
Some Problems with the Typological Species Concept
Hornlessmorph
Hornedmorph
Cline: a change in in morphology along an environmental gradient
Some Problems with the Typological Species Concept
Size in yarrow
Some Problems with the Typological Species Concept
Latitude
Drosophila subobscura
Cryptic species: some species are similar morphologically but differ in other important ways
Some Problems with the Typological Species Concept
Western meadowlark
Eastern meadowlark
What is a species?
Species Concepts:
2. Biological species concept: a species is a population or group of populations that can potentially interbreed and produce viable,fertile offspring, but that is reproductively isolated from other populations.
There is tremendous morphological variation within Homo sapiens. But all humans can potentially interbreed.
In contrast, some species are very similar morphologically but can not interbreed…
Western meadowlark Eastern meadowlark
Mechanisms of reproductive isolation:
1. Prezygotic barriers: prevent mating or fertilization
•Behavioral
Western meadowlark Eastern meadowlark
Mechanisms of reproductive isolation:
1. Prezygotic barriers: prevent mating or fertilization
•Behavioral
•Temporal
Western spotted skunk: summer breeder
Eastern spotted skunk: winter breeder
Mechanisms of reproductive isolation:
1. Prezygotic barriers: prevent mating or fertilization
•Behavioral
•Temporal
•Habitat isolation
Aquatic garter snake Terrestrial garter snake
Mechanisms of reproductive isolation:
1. Prezygotic barriers: prevent mating or fertilization
2. Postzygotic barriers: prevent hybrid from developing into a viable, fertile adult
Some problems with the biological species concept:
1. It is hard to apply especially to fossil data.
2. Species exist in time and space: the biological species concept has no time component.
3. What do we do with asexual organisms?
•Bdelloid Rotifers haven’t reproduced sexually for > 80 million years- each individual is reproductively isolated !
•An estimated 2000 species are completely asexual.
Species Concepts:
1. Typological species concept
2. Biological species concept
3. Evolutionary species concept• Incorporates time
4. Ecological species concept• Incoporates niche
5. Phylogenetic species concept• Incorporates unique, evolved traits
These have all been proposed to solve some of the problems of the other concepts
•To date > 1.5 million species of animals have been described by biologists
• ~ 10, 000 new species are described each year
•Estimates of the total number of animal species are around 10 million.
•How do biologists organize all of this diversity?
Classification and Phylogeny of Animals
•Taxonomy: the branch of biology that deals with the systematic classification and naming of species (or groups of species) (long pre-Darwinian history).
Carolus Linnaeus (1707- 1778)
•Swedish botanist
•Systema Naturae: a classification scheme that used morphology to group organisms into hierarchical categories
Taxonomy
Linnaean Classification
Kingdom
Phylum
Class
Order
Family
Genus
species
•In this scheme the major categories are called taxa
•Higher taxa are increasingly inclusive
•Each species is given a unique binomial name: Binomial nomenclature
Taxonomy
Linnaean Classification: an example
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Piciformes
Family: Picidae
Genus: Melanerpes
species: carolinus
Taxonomy
Linnaean Classification: another example
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Piciformes
Family: Picidae
Genus: Melanerpes
species: erythrocephalus
Taxonomy
Linnaean Classification: another example
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Piciformes
Family: Ramphastidae
Genus: Ramphastos
species: sulfuratus
Taxonomy
Keeled toucan
Linnaean Classification Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Subclass: Eutheria
Order: Primates
Suborder: Anthropoidea
Family: Pongidae
Subfamily: ~
Genus: Gorilla
species: gorilla
Taxonomy
Classification and Phylogeny of Animals
•Taxonomy: the branch of biology that deals with the systematic classification and naming of species (or groups of species) (long pre-Darwinian history).
•Systematics: the branch of biology that seeks to understand the evolutionary relationships between groups of organisms (post-Darwinian).
-One of the major goals of systematics is the construction of phylogenies
Systematics
Phylogeny: an evolutionary tree that depicts the relationships between living and extinct species (or higher taxonomic groups)
A CB D
Most recent common ancestor of C and D
Most recent common ancestor of A and B
Most recent common ancestor of A, B, C and D
What kind of information is used to construct phylogenies?
•Characters: organismal features that vary among species (morphological or molecular characteristics)
Systematics
Morphological characters used to construct phylogenies-
•Levels of organization:
1. Cellular level: an aggregation of cells that are functionally differentiated, but that are not organized into tissues
2. Tissue level: cells are organized into tissues that have a specific function
3. Organ level: tissues are aggregated into organs that have specialized functions
spongesjellyfish, corals, etc.
other animals
cellularlevel
tissue level
organ level
Morphological characters used to construct phylogenies
•Type of symmetry: the arrangement of body structures relative to some axis of the body
1. Asymmetrical:
2. Radial symmetry:
3. Bilateral symmetry:
Asymmetrical
Bilateral
Radial
No plane can divide the body into two symmetrical halves
> 1 plane can divide the body into two symmetrical halves
1 plane divides the body into two symmetrical halves
sponges
jellyfish, corals, etc.
other animals
asymmetrical
radial symmetry
bilateral symmetry
Characters used to construct phylogenies
•The presence of different body structures
•Developmental patterns
•Molecular data: DNA / RNA sequence data
What kind of information is used to establish these relationships?
•Characters: organismal features that vary among species (morphological or molecular characteristics)
•Homologous characters: characters that are similar to one another due to shared ancestry (not necessarily shared function)
Examples of homologous characters: Vertebrate forelimbs
•Analogous characters: characters that are similar to one another in function, but not ancestry.
•Analogous characters are not useful in determining the evolutionary relationships between organisms.
Examples of analogous characters: bat wings and insect wings
Bat wing Fly wing
Classification and Phylogeny of Animals
•Taxonomy: the branch of biology that deals with the systematic classification and naming of species (or groups of species) (long pre-Darwinian history).
•Systematics: the branch of biology that seeks to understand the evolutionary relationships between groups of organisms (post-Darwinian).