Chapter 1 exam 1 (lecture) Flashcards
Primitive structure definition
original condition of a trait in the common ancestor
Example of a primitive structure
All vertebrates, share the primitive trait of a backbone which was first seen in their common ancestor, the jawless fish.
Derived structure definition
modification of a primitive trait
example of a derived structure
feather and hair both epidermally derived but have modifications that are significantly different visually.
Homologous structure definition
structure found in two or more descendants of a common ancestor
-similar anatomical position but may not have same function or appearance
example of a homologous structure
the bones that make up the wings in pterodactyls, bats and birds (ulna, radius etc) are homologous
Analogous structure definition
structure in 2+ organisms that looks similar and is used for the same function but has evolved independently
analogous structures are produced via what kind of evolution?
convergent evolution
what is convergent evolution
independent species evolve similar traits via adaptation to similar environments with similar selective pressures
example of analogous structures
wings in pterodactyl, bat and bird evolved independently 3 times with analogous wing shape.
Exaptation
pre-existing structure that is inherited from an ancestor but is used for an unrelated function
example of exaptation
Dinosaurs and birds both have feathers
- pre adaptive structure (original feathers) were used from thermoregulation
-via descent with modification, feathers were used for flight
Phylogenetic tree
hypothesis of evolutionary progression/ relationships
Phylogeny is often visualized with
evolutionary trees
Phylogeny definition
study of evolutionary relatedness among past and present taxonomic groups (relationships among living things through time)
Systematics includes both:
- taxonomy
- phylogenetics
phylogenetics definition
determining the evolutionary relationships among organisms
What is binomial nomenclature
2 terms to denote extant or extinct species. Both latin or Greek and italicized
what does the first term indicate in binomial nomenclature? is it capitalized?
genus, capitalized
what does the second term indicate in binomial nomenclature? is it capitalized
specific epithet, not capitalized.
Who came up with using binomial nomenclature to describe taxonomy
Caroli Linnaei
In hierarchal classification, a named unit at any level of the hierarchy is considered a __________
taxon
Who introduced a more modern approach of phylogenetic tree construction, aka Cladistics?
entomologist Willi Henning in phylogenetic systematics
Cladistics is the classification of organisms based on _________ _________ characteristics that can be traced back to a groups most recent ancestor
Shared derived characteristics
what types of heritable attributes/ characteristics are used for recognizing, differentiating or classifying a taxon?
morphological, embryological, physiological, behavioral, genetic
What is a synapomorphy? Is it informative? provide an example.
-shared derived trait found in 2 or more taxa that are used to infer a phylogenetic relationship.
-informative
-ex: type of feather
What is a symplesiomorphy? Is it informative? provide an example.
-shared primitive trait that is relatively unchanged from the ancestral form
-not informative, tells us nothing about relatedness
-bird symplesiomorphies: feathers and beaks
What is an Autapomorphy? Is it informative? provide an example.
-a derived trait that is unique to only one group
-not informative, no shared trait therefore no relationship established
-ex: brain size in modern humans. not a trait shared by our closest relatives (chimpanzees or other hominins). distinguishes humans from other species but doesn’t help us determine the evolutionary relationships between humans, chimpanzees, and gorillas.
What is an Homoplasy? Is it informative? provide an example.
-derived trait found in 2 or more taxa that did not arise from a common ancestor (basically analogous structure)
-not informative. similar traits evolved independently therefore do not reflect shared ancestry
-ex:wings of bats and birds . bat wings evolved from mammalian forelimbs, while bird wings evolved from reptilian forelimbs. similarity in wing function and structure is due to response to similar environmental demands (flight), not because bats and birds share a recent common ancestor with wings.
Cladogram definition
branching diagram showing evolutionary relationships between taxa
T/F? evolutionary trees are an example of a cladogram
True
What is included in a Clade? what does it form?
-natural evolutionary lineage including the most recent ancestor and all of only that ancestors descendants
-forms a monophyly
Monophyly definition
-a complete clade
- consists of the most recent common ancestor and all of its descendants
Paraphyly definition
-an incomplete clade
-includes the most recent common ancestor but not all of its descendants
-aka homoplasy
example of a paraphyly
fish
-sarcopterygian fish gave rise to tetrapods therefore “fish” is a paraphyletic group unless tetrapods are included (would then be monophylitic)
polyphyly definition
an aritifical clade composed of unrelated organisms descended from more than one ancestor
polyphyly example
ex: mammals and birds are both warm blooded but evolved independently
sister taxa
groups of organisms that share immediate common ancestor and hence are each others closest relatives
Crown group definition
-includes the most recent common ancestor of all living taxa of a particular group (plus any extinct descendants
-as long as there is 1 living organism, it is a crown group
Stem group definition
-includes the extinct taxa related to but not part of the crown group
-extinct lineages that diverged below the most recent common ancestor of the group
-no living members
the total group is the sum of:
Crown group + stem group
isometric growth definition and example
-all structures of an organisms have the same rate of growth so that its shape is consistent throughout development
ex: salamander growth
allometric growth definition and example
-certain structures of an organisms have a differential rate of growth in an individual throughout development
ex: humans -babies grow into their bobble heads
The size of a species comes with what constraints? What do larger organisms need to get around these constraints? provide an example
- as a species increases in size, its volume and mass (proportional to volume) increases faster than surface area
-larger organisms need morphological specializations to allow for enough physiological exchange (gas and heat exchange, nutrient absorption)
-ex: cilli and micovilli increase the surface area in gut to absorb nutrients, elephants have large ears to dissipate heat
Heterochrony definition
-evolutionary changes in the timing or rate of developmental processes
-can lead to alterations in size, shape, and morphology between ancestors and their descendants.
-these changes can affect when certain traits/ structures appear or how long certain structures continue to develop
Paedomorphosis definition
-“child form”
-juvenile traits of ancestors appear in the adults of descendants
- includes progenesis and neoteny
neoteny definiton. provide an example
-Definition: Somatic (body) development slows down or is delayed, resulting in the retention of juvenile physical traits, but the organism eventually reaches sexual maturity.
-Key Mechanism: The overall development of the body is slowed, but reproduction happens at the usual time.
-chimp reproductive age is about the same as humans therefore humans likely developed in neotonic way
Progenesis
-Definition: Reproductive development is accelerated, meaning the organism reaches sexual maturity earlier while its somatic (body) development remains in a juvenile form.
-Key Mechanism: Early reproductive maturity, but overall body development is not delayed; it just stops early.
Peramorphosis definition
-“beyond form”
-organism’s development is extended beyond the typical endpoint seen in its ancestors. results in exaggerated/advanced traits compared to ancestral form.
-involves the prolongation or acceleration of developmental processes, leading to traits that are “beyond” what would normally appear in the ancestral species.
hypermorphosis definition
-organism’s traits continue to develop for a longer time than usual, creating features that are larger or more complex than those of its ancestors.
-ex: irish elk
unusually large antlers grew for an extended period compared to its ancestors, leading to an exaggerated size as a result of prolonged development.
acceleration definition (in terms of peramorphosis)
-growth rate of certain traits is faster than in the ancestral form.
-leads to the exaggerated or advanced appearance of those traits in the adult organism.
-involves reaching the final adult form more quickly, but with more pronounced traits.
