8 public questions tagged with this topic.
Semelparity is a reproductive strategy where organisms reproduce once before dying, as seen in certain insects and salmon.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Population Interactions - Parasitism and Commensalism
Under the graphical convention used in this life-history model, a concave-upward relationship favors concentrating reproductive effort into a single event, hence semelparity. Curvature determines whether fitness gains accelerate as more resources are committed. If a large one-time allocation yields disproportionately greater fecundity than several smaller allocations, preserving resources for another season is less advantageous. Selection can favor a large terminal effort when future survival is poor or when concentrating resources yields accelerating fecundity gains. Repeated breeding is favo
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 5
The supplied key links semelparity with uncertain offspring survival, but that statement is not generally reliable. When reproductive success varies unpredictably among years and adults survive well, iteroparity often spreads risk across seasons. Semelparity is instead favored when survival to another breeding opportunity is low or when concentrating resources produces a disproportionately large fecundity gain. Thus the keyed condition alone does not establish the claimed strategy. The evolutionary currency is lifetime reproductive success, not the number of offspring in one event. Present rep
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 5
Coho salmon are semelparous: adults migrate to freshwater, invest heavily in one spawning season, and die after reproduction. Their stored energy is spent on migration, competition, nest construction, gamete production, and defense rather than future survival. Loggerhead turtles and long-lived trees generally reproduce in multiple years, making them iteroparous. Selection can favor a large terminal effort when future survival is poor or when concentrating resources yields accelerating fecundity gains. Repeated breeding is favored when adults commonly survive and spreading reproduction buffers
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 5
Dracaena is treated here as the non-semelparous organism because many species are perennial plants capable of flowering repeatedly. Bamboo, cicadas, and mayflies include familiar examples that invest in a single major reproductive episode or effectively reproduce once before death. Taxonomic names alone can conceal variation, however: semelparity must ultimately be established from the life history of the particular species, not assumed for every member of a genus. The r/K framework is best treated as a continuum. At one end, rapid development and many inexpensive offspring suit transient oppo
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
Semelparity means concentrating reproduction into one episode, usually followed by death, whereas iteroparity means reproducing on two or more occasions. These are contrasting life-history schedules. An annual organism need not be semelparous in the broader sense, and fecundity measures offspring production rather than the number of reproductive episodes, so neither term is the conceptual opposite. Life-history traits should be interpreted as correlated tendencies rather than rigid packages. Adult survival, juvenile mortality, body size, development time, fecundity, and parental investment int
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
The keyed exception is “C and D favor semelparous.” In the context of csir-net: which trait does not favor semelparity, that statement differs from the governing ecological pattern and must be evaluated against the mechanism rather than accepted from wording alone. Survivorship curves summarize age-specific mortality: Type I concentrates loss late in life, Type II approximates a constant hazard, and Type III concentrates loss early. They are empirical patterns, not rigid taxonomic rules. The remaining alternatives—“A and B curves are concave”, “A and B favor semelparous”, “C and D favor iterop
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
“Semelparous species” for mayflies, salmon, and annual grains are examples of. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Interpretation must distinguish absolute population change from a per-capita rate and must state the time interval and population boundary. Age structure, dispersal, environmental variation, and delayed responses can all make observed trajectories depart from a simple model. The remaining alternatives—“Iteroparous species”, “Viviparous species”, “Precocial species”—refer t
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
