ZOO 4910 Lecture Notes - Lecture 2: Bald Eagle, Haikouella, Vertebrate
2 May 2018
School
Department
Course
Professor
Vertebrates are diverse (but far less so than invertebrates)
•
Many systematic relationships remain ambiguous
•
Vertebrate groups have evolved in a changing physical and
biological environment
•
Vertebrate diversity (and classification) applies today
•
Key Themes:
Notochord
1.
Pharyngeal slits
2.
Dorsal hollow nerve cord
3.
Postanal tail
4.
Endostyle
5.
At some point during development, all chordates have:
Fossil formations were found in China
•
Very similar to sea squirts
•
Contain all chordate characteristics
•
Vertebrate Origins: Haikouella from Chenjiang Cambrian fauna
~50% are fish
○
~63,000 species
•
All have "metamerically arranged endoskeleton elements flanking
the spinal cord" (vertebrae)
•
Most have jaws (except lamprey and hagfish)
•
In most vertebrates, a notochord is only found in embryos
•
~60-70% are insects
○
Small percentage are vertebrates
○
Chordate diversity:
•
Defining Vertebrata:
Mammals -5,416
•
Birds -9,993
•
Reptiles -10,450
•
Amphibians -7,707
•
Fishes -~30,000
•
Vertebrate Classes:
Some of the flying reptiles were smaller than a bald eagle
○
Pterosaurs were not all super-sized in the late Cretaceous
•
Ongoing research into the fossil record expands and refines out
idea of vertebrate diversity and evolution
•
Diversity in the Past:
Diversity: how many species there are in a group
•
Disparity: how different members of a group are from each other
•
Diversity vs. Disparity:
Diversification through speciation1)
Loss of diversity through extinction2)
Taxonomic diversity is the net outcome of two opposing processes:
*difference in diversity among groups reflect differences in relative rates
of speciation and extinction
See slide on evolution of vertebrates from various eras
•
First was ~440 million years ago
○
Second was ~370 million years ago (many scaled fishes were
lost)
○
Between paleozoic and mesozoic eras (permian -
triassic)
!
Could be due to massive environmental change/event
that most organisms could not adapt to
!
Third (most pronounced) was ~251 mya (origin era of the
dinosaurs)
○
Dramatic shifts gave rise to other species in this
transitional period
!
Shortly after, birds arose from this lineage
!
Fourth was ~200 mya (many reptiles)
○
Massive extinction of dinosaurs
!
Could be mediated by meteor that resulted in a
massive cooling of the planet
!
Fifth was ~65 mya (cretacous -tertiary in cenozoic)
○
5 mass extinctions through time --> speciation
•
Diversity varies among groups and over time within groups
Kingdom -Animalia
○
Phylum (& subphylum) -Chordata (Vertebrata)
○
Class -Mammalia
○
Order -Primates
○
Family -Hominidae
○
Genus -Homo
○
Species -Sapiens
○
Taxonomic System:
•
Linnaeus' hierarchical taxonomic system works due to arrangement
of similarity via evolution and common ancestry
•
Classifying Canids: Canis lupus familiaris (dogs)
•
Classification of Phylogenetics:
Ernest Mayr (1904-2005) introduced the Biological Species
Concept
•
"group of actually or potentially interbreeding individuals
that are reproductively isolated from other such groups"
○
Recognizes fewer species but classifies more subspecies
○
"lumpers"
○
Biological Species Concept:
•
A group of individuals all descended from a common
ancestor and that share certain defining or derived traits
○
Phylogenetic Species Concept:
•
Morphological species
○
Recognizes more species but fewer subspecies
!
"splitters"
!
Genetic species
○
Other Concepts:
•
Defining 'Species':
Build a diagram using derived characters
•
Clade Tetropoda -four limbs (amphibians)
○
Clade Amniota -aminotic egg (reptiles)
○
Clade Mammalia -hair (marsupials)
○
Clade Carnivora -specialized shearing teeth (dogs and
relatives)
○
Clade Felidae -retractable claws (cats)
○
Example:
•
Cladistics:
A "natural" classification system is not based on superficial
similarity but on evolutionary relatedness
•
According to cladistics, only monophyletic groups should receive
taxonomic names
•
Composed of a collection of organisms, including the most
recent common ancestor of those organisms and ALL the
descendants of that most recent ancestor
○
Monophyletic Group:
•
Composed of a collection of organisms, including the most
recent common ancestor but does not include all of the
descendants from that ancestor
○
Paraphyletic Group:
•
Composed of a collection of organisms in which the most
recent common ancestor of all organisms considered is not
included (usually because the common ancestor lacks the
characteristic of the group)
○
Shows evidence of convergent evolution
!
Dolphins & whales, walruses, manatees
!
E.g. marine mammals -arose from three different
mammalian orders
○
Polyphyletic Group:
•
Phylogenetics and "Natural" Classification
Use multiple nuclear and mtDNA genes to assess divergence1.
Need to assess 'direction' and level of introgression in hybrids 2.
*target: % divergence cut off
Baker & Bradley -Genetic Species Concept in Mammals
Genetic Species Concept: A group of genetically compatible
interbreeding populations that are genetically isolated from other such
groups
Genes diverge to stage where they do not function well in a 'sister'
species (levels of hybrid inviability)
•
Cytoplasmic (mtDNA) -nuclear incompatibility
•
Genetic changes bring about changes in behaviour
•
Genetic changes in chemical signals (phermones)
•
Chromosomal rearrangements
•
Genetic Isolation:
Need nuclear genes to determine if it is a hybrid
•
Type A/B -unidirectional (greater genetic incompatibility)
○
Type A and B -bidirectional
○
Hybrid mtDNA haplotype:
•
Hybrids:
Taxonomic classification is controversial, initially a relative of the
raccoon (Procyonidae) then reclassified into Ursidae
•
Based on fossil record, serology, karyology, behaviour, anatomy
•
Ex. Classification of the Red Panda -Ailurus fulgens
New paper suggests that there are four different species of giraffe
based on nuclear DNA data
•
Geographic separation and synchronization to produce
young in the wet seasons may keep them separate
○
Females produce young in the wet season as it is most
favourable for growth
○
Problem: giraffes will mate in zoo environments
•
Behavioural Species?
Overview of Vertebrate Diversity
Wednesday,* September* 13,*2017
12:29*PM
Vertebrates are diverse (but far less so than invertebrates)
•
Many systematic relationships remain ambiguous
•
Vertebrate groups have evolved in a changing physical and
biological environment
•
Vertebrate diversity (and classification) applies today
•
Key Themes:
Notochord1.
Pharyngeal slits2.
Dorsal hollow nerve cord3.
Postanal tail4.
Endostyle 5.
At some point during development, all chordates have:
Fossil formations were found in China
•
Very similar to sea squirts
•
Contain all chordate characteristics
•
Vertebrate Origins: Haikouella from Chenjiang Cambrian fauna
~50% are fish
○
~63,000 species
•
All have "metamerically arranged endoskeleton elements flanking
the spinal cord" (vertebrae)
•
Most have jaws (except lamprey and hagfish)
•
In most vertebrates, a notochord is only found in embryos
•
~60-70% are insects
○
Small percentage are vertebrates
○
Chordate diversity:
•
Defining Vertebrata:
Mammals -5,416
•
Birds -9,993
•
Reptiles -10,450
•
Amphibians -7,707
•
Fishes -~30,000
•
Vertebrate Classes:
Some of the flying reptiles were smaller than a bald eagle
○
Pterosaurs were not all super-sized in the late Cretaceous
•
Ongoing research into the fossil record expands and refines out
idea of vertebrate diversity and evolution
•
Diversity in the Past:
Diversity: how many species there are in a group
•
Disparity: how different members of a group are from each other
•
Diversity vs. Disparity:
Diversification through speciation
1)
Loss of diversity through extinction
2)
Taxonomic diversity is the net outcome of two opposing processes:
*difference in diversity among groups reflect differences in relative rates
of speciation and extinction
See slide on evolution of vertebrates from various eras
•
First was ~440 million years ago
○
Second was ~370 million years ago (many scaled fishes were
lost)
○
Between paleozoic and mesozoic eras (permian -
triassic)
!
Could be due to massive environmental change/event
that most organisms could not adapt to
!
Third (most pronounced) was ~251 mya (origin era of the
dinosaurs)
○
Dramatic shifts gave rise to other species in this
transitional period
!
Shortly after, birds arose from this lineage
!
Fourth was ~200 mya (many reptiles)
○
Massive extinction of dinosaurs
!
Could be mediated by meteor that resulted in a
massive cooling of the planet
!
Fifth was ~65 mya (cretacous -tertiary in cenozoic)
○
5 mass extinctions through time --> speciation
•
Diversity varies among groups and over time within groups
Kingdom -Animalia
○
Phylum (& subphylum) -Chordata (Vertebrata)
○
Class -Mammalia
○
Order -Primates
○
Family -Hominidae
○
Genus -Homo
○
Species -Sapiens
○
Taxonomic System:
•
Linnaeus' hierarchical taxonomic system works due to arrangement
of similarity via evolution and common ancestry
•
Classifying Canids: Canis lupus familiaris (dogs)
•
Classification of Phylogenetics:
Ernest Mayr (1904-2005) introduced the Biological Species
Concept
•
"group of actually or potentially interbreeding individuals
that are reproductively isolated from other such groups"
○
Recognizes fewer species but classifies more subspecies
○
"lumpers"
○
Biological Species Concept:
•
A group of individuals all descended from a common
ancestor and that share certain defining or derived traits
○
Phylogenetic Species Concept:
•
Morphological species
○
Recognizes more species but fewer subspecies
!
"splitters"
!
Genetic species
○
Other Concepts:
•
Defining 'Species':
Build a diagram using derived characters
•
Clade Tetropoda -four limbs (amphibians)
○
Clade Amniota -aminotic egg (reptiles)
○
Clade Mammalia -hair (marsupials)
○
Clade Carnivora -specialized shearing teeth (dogs and
relatives)
○
Clade Felidae -retractable claws (cats)
○
Example:
•
Cladistics:
A "natural" classification system is not based on superficial
similarity but on evolutionary relatedness
•
According to cladistics, only monophyletic groups should receive
taxonomic names
•
Composed of a collection of organisms, including the most
recent common ancestor of those organisms and ALL the
descendants of that most recent ancestor
○
Monophyletic Group:
•
Composed of a collection of organisms, including the most
recent common ancestor but does not include all of the
descendants from that ancestor
○
Paraphyletic Group:
•
Composed of a collection of organisms in which the most
recent common ancestor of all organisms considered is not
included (usually because the common ancestor lacks the
characteristic of the group)
○
Shows evidence of convergent evolution
!
Dolphins & whales, walruses, manatees
!
E.g. marine mammals -arose from three different
mammalian orders
○
Polyphyletic Group:
•
Phylogenetics and "Natural" Classification
Use multiple nuclear and mtDNA genes to assess divergence1.
Need to assess 'direction' and level of introgression in hybrids 2.
*target: % divergence cut off
Baker & Bradley -Genetic Species Concept in Mammals
Genetic Species Concept: A group of genetically compatible
interbreeding populations that are genetically isolated from other such
groups
Genes diverge to stage where they do not function well in a 'sister'
species (levels of hybrid inviability)
•
Cytoplasmic (mtDNA) -nuclear incompatibility
•
Genetic changes bring about changes in behaviour
•
Genetic changes in chemical signals (phermones)
•
Chromosomal rearrangements
•
Genetic Isolation:
Need nuclear genes to determine if it is a hybrid
•
Type A/B -unidirectional (greater genetic incompatibility)
○
Type A and B -bidirectional
○
Hybrid mtDNA haplotype:
•
Hybrids:
Taxonomic classification is controversial, initially a relative of the
raccoon (Procyonidae) then reclassified into Ursidae
•
Based on fossil record, serology, karyology, behaviour, anatomy
•
Ex. Classification of the Red Panda -Ailurus fulgens
New paper suggests that there are four different species of giraffe
based on nuclear DNA data
•
Geographic separation and synchronization to produce
young in the wet seasons may keep them separate
○
Females produce young in the wet season as it is most
favourable for growth
○
Problem: giraffes will mate in zoo environments
•
Behavioural Species?
Overview of Vertebrate Diversity
Wednesday,* September* 13,*2017 12:29*PM
