新物種的出現(xiàn)分為兩種情況：通常情況下是由于配偶選擇特異性導致的基因隔離，當雜交不能進行時,，新物種便產生了,；還有一種較為少見的同域物種生成作用（sympatric speciation），指的是新物種出現(xiàn)于沒有地理和物理隔離的單一群體中,。同域物種生成作用最為典型的例子是蘋果實蠅,，這種實蠅曾以山楂樹果實為食，隨后開始以蘋果為食,，繼而進化出了基因型完全不同的新蠅類,。數(shù)學模型研究顯示，配偶選擇,、競爭,、可用資源多樣性是引起同域物種生成作用的三大關鍵因素。
圖：蘋果實蠅
國立數(shù)學與生物合成研究所的博士后X.Thibert-Plante與麥吉爾大學的A.P.Hendry副教授采用了新的研究模型對同域物種生成作用進行了研究,，較之以前的僅關注一兩項因素的研究模型,，新研究模型能夠同時關注三大關鍵因素。Thibert-Plante說,，新模型能夠使他們綜合考慮各項因素的影響以及它們相互之間的關系,，至少，可用資源的多樣性是形成生物多樣性的一個有效途徑,。結果顯示,，個體間競爭較其他兩項因素相比，就顯得不那么重要了,。
不過,，就算是在理想狀況下，同域物種生成作用也極少在模型中發(fā)生,。但這并不意味著,，它在自然界就不重要了，有一點可以明確,，配偶選擇可使群體基于資源而變得更為專門化,，也使個體更加多產。（生物谷Bioon.com）
生物谷推薦原文出處：
European Society For Evolutionary Biology doi:10.1111/j.1420-9101.2008.01627.x
Five questions on ecological speciation addressed with individual-based simulations
X.Thibert Plante,，A.P.Hendry
We use an individual-based simulation model to investigate factors influencing progress toward ecological speciation. We find that environmental differences can quickly lead to the evolution of substantial reproductive barriers between a population colonizing a new environment and the ancestral population in the old environment. Natural selection against immigrants and hybrids was a major contributor to this isolation, but the evolution of sexual preference was also important. Increasing dispersal had both positive and negative effects on population size in the new environment and had positive effects on natural selection against immigrants and hybrids. Genetic divergence at unlinked, neutral genetic markers was low, except when environmental differences were large and sexual preference was present. Our results highlight the importance of divergent selection and adaptive divergence for ecological speciation. At the same time, they reveal several interesting nonlinearities in interactions between environmental differences, sexual preference, dispersal and population size.
