Burgess Scott C, Speare Kelly E, McLachlan Rowan H, Johnston Erika C, Adam Thomas C, Vega Thurber Rebecca, Burkepile Deron E
Department of Biological Science, Florida State University, Tallahassee, Florida, USA.
Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, USA.
Ecology. 2025 May;106(5):e70079. doi: 10.1002/ecy.70079.
Cryptic species (evolutionarily distinct lineages that do not align with morphologically defined species) are being increasingly discovered but are poorly integrated into ecological theory. In particular, we still lack a useful understanding of if and how cryptic species differ in ways that affect community recovery from disturbances and responses to anthropogenic stressors, such as the removal of consumers and pollution from nutrients. On coral reefs, nutrient pollution increases the growth of macroalgae that displace corals. Reductions in herbivorous fishes reduce the suppression of macroalgae, while reductions in coralivorous fishes reduce predation on corals. An unresolved question is if and how cryptic coral species respond differently to these impacts, thereby differing in their ability to influence coral community dynamics and maintain coral dominance. Therefore, we assessed how the response of cryptic Pocillopora species over a period of three years following a simulated disturbance from a cyclone depended on the experimental reduction of fish consumer pressure and nutrient addition. After three years, five morphologically cryptic, but genetically distinct, Pocillopora species recruited to the reef. However, recruitment was dominated by two species: Pocillopora tuahiniensis (46%) and Pocillopora meandrina (43%). Under ambient conditions, recruitment of P. tuahiniensis and P. meandrina was similar, but experimentally reducing consumer pressure increased recruitment of P. tuahiniensis by up to 73% and reduced recruitment of P. meandrina by up to 49%. In both species, nutrient enrichment increased recruitment and colony growth rates equally, but colonies of P. tuahiniensis grew faster and were up to 25% larger after three years than those of P. meandrina, and growth was unaffected by reduced consumer pressure. Predation by excavating corallivorous fish was higher for P. meandrina than for P. tuahiniensis, especially under nutrient enrichment. In contrast, polyp extension (an indicator of elevated heterotrophic feeding as well as susceptibility and attractiveness to corallivores) was lower for P. meandrina than for P. tuahiniensis, especially under low to medium consumer pressure. Overall, we uncovered ecological differences in the response of morphologically cryptic foundation species to two pervasive stressors on coral reefs. Our results demonstrate how cryptic species respond differently to key anthropogenic stressors, which may contribute to response diversity that can support ecological resilience or increase extinction risk.
隐存种（即进化上不同但与形态学定义的物种不一致的谱系）正越来越多地被发现，但在生态理论中却未得到很好的整合。特别是，我们仍然缺乏对隐存种是否以及如何以影响群落从干扰中恢复以及对人为压力源（如去除消费者和营养物质污染）作出反应的方式存在差异的有用理解。在珊瑚礁上，营养物质污染会增加大型藻类的生长，从而取代珊瑚。草食性鱼类数量的减少会降低对大型藻类的抑制作用，而食珊瑚鱼类数量的减少则会降低对珊瑚的捕食。一个尚未解决的问题是隐存珊瑚物种是否以及如何对这些影响作出不同反应，从而在影响珊瑚群落动态和维持珊瑚优势地位的能力方面存在差异。因此，我们评估了在模拟飓风干扰后的三年时间里，隐存的鹿角杯形珊瑚物种的反应如何取决于对鱼类消费者压力的实验性降低和营养物质添加。三年后，有五种形态上难以区分但基因上不同的鹿角杯形珊瑚物种在珊瑚礁上定居。然而，定居主要由两个物种主导：图阿希尼鹿角杯形珊瑚（46%）和梅氏鹿角杯形珊瑚（43%）。在环境条件下，图阿希尼鹿角杯形珊瑚和梅氏鹿角杯形珊瑚的定居情况相似，但通过实验降低消费者压力使图阿希尼鹿角杯形珊瑚的定居率提高了多达73%，并使梅氏鹿角杯形珊瑚的定居率降低了多达49%。在这两个物种中，营养物质富集同样提高了定居率和群体生长率，但三年后，图阿希尼鹿角杯形珊瑚的群体生长得更快，比梅氏鹿角杯形珊瑚的群体大25%，并且生长不受消费者压力降低的影响。挖掘性食珊瑚鱼类对梅氏鹿角杯形珊瑚的捕食高于图阿希尼鹿角杯形珊瑚，尤其是在营养物质富集的情况下。相比之下，梅氏鹿角杯形珊瑚的珊瑚虫伸展（异养摄食增加以及对食珊瑚动物的易感性和吸引力的一个指标）低于图阿希尼鹿角杯形珊瑚，尤其是在低到中等消费者压力下。总体而言，我们发现了形态上难以区分的基础物种对珊瑚礁上两种普遍存在的压力源的反应存在生态差异。我们的结果表明了隐存种对关键人为压力源的不同反应方式，这可能有助于形成能支持生态恢复力或增加灭绝风险的反应多样性。
