Citat:
Īn prealabil postat de Callisto
Zona crepusculara...
Din raspunsul tau (ca intotdeauna lapidar ) nu pot sa inteleg cum lipsa definirii conceputului central dintr-o teorie arata ca teoria functioneaza ; ai vrut sa zici ca trebuie sa mai evoluam si noi ca sa ne dam seama ce e o specie ?
|
Am spus doar ca tinem la a exista conceptul de specie si deci la o definitie a ei din chestiuni practice, pentru o mai usoara clasificare a fiintelor.
Pentru ca aceasta definitie si clasificare sa fie practica trebuie sa avem un numar mic de criterii, unitare.
Chiar si cu un numar minim de criterii rezulta zeci de milioane de specii. Daca numarul de criterii s-ar mari, problemele cu definitia speciei s-ar rezolva in mare parte dar ar deveni total inutila, pina la a ajunge ca fiecare organism sa fie declarat o specie.
Citat:
Īn prealabil postat de Callisto
Deci, avem urmatoarele chestiuni 1. Mayr da o definitie care nu e unanim acceptata, dar e cel mai bun lucru avut pana una alta 2. Grangurii Bobo si Bubu au fost stabiliti ca specii diferite, numai ca ei adeseori se imperecheaza 3. Acest FAPT contrazice definitia biologului mai sus amintit 4. Unii nu vad in asta nici o problema.
|
p. 737. Split Icterus galbula into I. galbula, I. bullockii, and I. abeillei, which revert to their former English names.
The northern species, galbula and bullockii, were merged because of hybridization in the Great Plains (Sibley and Short 1964).
However, the hybrid zone apparently is stable, with little apparent introgression beyond its boundaries, and the occurrence of pure parental types versus free interbreeding is temporally variable at several sites (Corbin and Sibley 1977, Rising 1983).
We prefer to treat these taxa as biological species because the number of important differences between them suggest that gene flow is restricted. They differ in: male, female and immature plumages; vocalizations (Rising 1970); thermoregulatory abilities (Rising 1969); allele frequencies (Corbin et al. 1979); number of molts and molt-migration schedule (Rohwer and Manning 1990); nest-site place- ment and dispersion (Rising 1970); and body size (Sibley and Short 1964, Rising 1973, 1983). We know of no other case where there are so many discrete, abrupt, concordant differences between populations treated as one species. Icterus abeillei was long ago merged with I. bullockii on the basis of hybridization in Durango reported by Miller (1906). His description of spec- imens from the small sample, however, indicated that interbreeding was not free and that individuals were near I. bullockii. The oriole population at that locality is intermittent (Rising 1973). These facts plus the striking plumage differences between these forms argue for species status.
Asta e motivarea AOU din 1995
Citat:
Īn prealabil postat de Callisto
Inainte sa intru pe forumul asta habar nu aveam cita ignoranta (mai bine spus, refuz de a vedea lucrurile clar) poate sa incorporeze actul subscrierii la evolutionism.
|
Multi cred ca stiinta se face pocnind din degete