Quote:
Originally Posted by jefta
ja tylko dodam od siebie, ze psy powyzej 70 cm maja powazne problemy z wytrzymaniem treningu obronnego-kregoslup nie wytrzymuje. Sa tez duzo mniej skuteczne-mala zwinnosc i dynamika.
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I mamy wytlumaczenie dlaczego uzytki nie sa wielkie...
Znalazlam prace naukowa pod tytulem:
Wielkosc ciala a wyniki drapieznosci [sukcesy w polowaniu] u wilkow: czy wieksze jest lepsze? ((MacNulty, Smith, Mech, Eberly; 2009)
Summary:
1. Large body size hinders locomotor performance in ways that may lead to trade-offs in predator foraging ability that limit the net predatory benefit of larger size. For example, size-related improvements in handling prey may come at the expense of pursuing prey and thus negate any enhancement in overall predatory performance due to increasing size.
2. This hypothesis was tested with longitudinal data from repeated observations of 94 individually known wolves (Canis lupus) hunting elk (Cervus elaphus) in Yellowstone National Park, USA. Wolf size was estimated from an individually based sex-specifc growth model derived from body mass measurements of 304 wolves.
3. Larger size granted individual wolves a net predatory advantage despite substantial variation in its effect on the performance of different predatory tasks; larger size improved performance of a strength-related task (grappling and subduing elk) but failed to improve performance of a locomotor-related task (selecting an elk from a group) for wolves > 39 kg.
4. Sexual dimorphism in wolf size also explained why males outperformed females in each of the three tasks considered (attacking, selecting, and killing).
5. These fndings support the generalization that bigger predators are overall better hunters, but they also indicate that increasing size ultimately limits elements of predatory behaviour that require superior locomotor performance. We argue that this could potentially narrow the dietary niche of larger carnivores as well as limit the evolution of larger size if prey are substantially more diffcult to pursue than to handle.
W skrocie: im wiekszy wilk tym skuteczniej zabija zwierzeta. Jednak wielkosc ma negatywny wplyw na lokomotoryke - byl widoczny "skok" u wilkow przy 39 kg. Te ktore mialy wiecej kg wolniej startowaly za zwierzyna, gorzej szlo im w pogoni za nia (mialy gorsza zwinnosc, zwrotnosc, itd), wiec mialy mniejsza skutecznosc lowow.
Wielkosc pomaga wilkom tam, gdzie zwierzyna jest duza i jest jej duzo.
Wilki zawsze sa mniejsze, gdy zyja na terenie, gdzie trzeba zwierzyne scigac i jest ona mniejsza (tak jak wlasnie nasze lasy, gdzie mamy glownie sarenki, a nie jelenie, wiec zwierzyne, ktora wazy jakies 50 a nie 500kg
). Natura sama nie pozwala przekroczyc wilkom granicy tych 39kg (najbardziej prawdopodobne "widelki" to 35–42kg).