4. Phylogeny & Reproduction Flashcards
Phylogeny
The origin and diversification of any taxon, or the evolutionary history of its origin and diversification
Homology
Character similarity resulting from common ancestry
Homoplasy
non-homologous similarities that may be found in various organisms
Birds wings vs Bats wings
Homoplasy and homology
Wings itself - homoplasy
Forelimbs - homology
Cladistics
An approach or methodology for classifying organisms based on common evolutionary descent
Cladistics accomplished by
Comparing characters - can be morphological, chromosomal or molecular
- Sometimes even behavioral
Phylogenetic Tree
Branching diagram showing the inferred evolutionary relationships among various biological species
Cladogram
A diagram used in cladistics to show evolutionary relationships between organisms
Clade
a unit of evolutionary common descent that includes ancestral lineage and all descendants
Character
an organismal feature that varies between species
Ancestral Character
Character state present in the common ancestor
Derived character
all other variant forms of the character that rose later within the group
Monophyletic clade
includes the most recent common ancestor all descendants of that ancestor
Paraphyletic clade
includes the most recent common ancestor and some but not all descendants of that ancestor
Polyphyletic clade
does not include the most recent common ancestor of all members of the group
Sexual Reproduction
Reproduction through the fusion of two specialized cells-gametes
Asexual reproduction
involves only one parent
No special reproductive organs or cells
Genetically identical offspring
Advantage of Asexual Reproduction
Quick and energy efficient
Sexual reproduction takes about twice as long
Disadvantages of Asexual Reproduction
Phenotypic diversity depends on mutation only
Muller’s ratchet: Accumulation of deleterious mutations
Advantages of sexual reproduction
Ability to mix and match successful genes
Disadvantages of sexual reproduction
Energetically costly
Males do not directly produce offspring
Binary Fission
Mitosis leads to individual organisms
Common among bacteria and protozoa
Schizogony
Multiple fission
nucleus divides repeatedly
Cytoplasmic division then produces many daughter cells
Budding
Unequal division of an organism
Bud is an outgrowth of the parent
Develops organs and then detaches
Gemmulation
Formation of a new individual from an aggregation of cells
Cells are surrounded by a resistant capsule - a “gemmule
Fragmentation
“Binary Fission” for multicellular organisms
Breaks into parts that become a new individual
Bisexual Reproduction
Most common form of sexual reproduction
Hermaphroditism
자웅동체
Male and female organs occur in same individual
Most avoid self-fertilization
Parthenogenesis
-Can be asexual
Embryo develops from unfertilized egg
Sperm may activate but not fuse with egg
Dioecious
Having male and female gonads in separate individuals
Monoecious
Having both male and female gonads in the same organism
Oviparous
Eggs are released by female
Development occurs outside the maternal body
Viviparous
Eggs develop within the female body, which provides nutritional aid
Internal fertilization
Ovoviviparous
- Reproduction in which eggs develop within the maternal body without additional nourishment from the parent
- Hatch within parent or immediately after laying
- Internal Fertilization
