Functional niche differentiation in co-occurring congeneric plants
Notice bibliographique
Résumé
Niche differentiation is argued as one of the mechanisms explaining species coexistence. Despite their sessile nature, similar resource needs and traits to acquire and utilize resources closely related plant species coexist. I hypothesized that i) spatial distribution of congeneric species would be similar because they are closely related with similar traits and resource needs and ii) each species will perform different biological functions (growth vs. reproduction) optimally at different points along a resource gradient and thereby differentiate their functional niche to ensure coexistence by complementary resource use. I collected data on two congeneric wild blueberry species, Vaccinium angustifolium and V. myrtilloides on occurrence from 13,500 20 x 20 cm quadrates, their growth and reproductive response to light and microhabitat parameters from 360 1 x 1 m quadrates along 90 30 m transects from 5 regions of NW Ontario. I also grew these two species in a common garden experiment (CGE) under a shade gradient to test their response to light in competition-free environment. A chi-square test confirmed that V. angustifolium and V. myrtilloides are co-occurring species. Variance partitioning analysis revealed that light is the most important microsite variable. Frequency of occurrence showed their abundance gradually increase from low to high light with high niche overlaps. Regression model fitting of cover (indicating growth) and berry yield (indicating reproduction) along the light gradient provided species functional response curves. By rescaling the response curves I obtained comparable functional fitness/performance curves, which showed that for both species optimum performance for growth and reproduction peaked at different light levels in natural habitats and in CGE. But their niche overlaps between growth and reproduction functions were markedly lower in natural habitats than in CGE meaning that these congeneric species differentiate their niche preferences for growth and reproduction. Both species showed conspicuous shift of functional niche in natural habitats from the CGE. Higher growth of one species was often corresponded with lower growth of the other suggesting a complimentary use of finite growing space. These results suggest that neighbouring plants may reduce their competitive stress by adjusting their biological functions through functional niche differentiation. To my knowledge this is the first study providing clear quantitative evidence of functional niche differentiation in two closely related coexisting plants. One of the mechanisms by which clonal understory woody plants avoid competition for light is through differentiating ?physical space niches? by foraging small resource patches by clonal extension. The results of my study reveal another mechanism of species co-existence, which has evolutionary significance. I show how two congeneric clonal species occupying the same physical niche space can avoid competition by differentiating their functional niche. Further discovery of functional niche differentiation in multiple coexisting species along multiple resource gradients (such as soil nutrients, soil moisture) will make a significant contribution to refining community assembly rules.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».