secondary reproduction burst in fall, when Cocconeis spp. are less abundant on the
leaves of the plant. Co-evolutionary relationships are often viewed in light of
mutual cooperation between two species. However, the peculiar case of H. inermis
indicates the need to widen the concept, integrating various adaptations that may
lead to different degrees of advantages for two co-evolving organisms. Shrimp’s
populations are stabilized in P. oceanica meadows thanks to this very specific
relationship, and they can survive a high predation pressure by fish and other
invertebrates because the secondary reproductive burst in fall produces sufficient
specimens for the next spring.
Keywords
Chemical ecology · Adaptation · Co-existence · Feeding · Food webs · Apoptosis
1
Introduction
Co-evolutionary processes often lead to mutualistic associations where two partners gain reciprocal advantages from the interactions in the same environment [1],
by following a process of joint adaptations between species [2]. The concept was
initially developed to explain the evolutionary forces driving the selection of two
species having close physiologic or ecologic relationships, to obtain mutual advantages. In contrast, the example of the shrimp Hippolyte inermis and the diatoms of
the genus Cocconeis indicates the evolution of a struggle for survival, leading to
organic diversification of both species, aimed at surviving in a complex but
relatively stable environment as the one represented by Posidonia oceanica
meadows. Since the infancy of coevolution studies, “the examination of patterns
of interaction between two major groups of organisms with a close and evident
ecological relationship, such as plants and herbivores” is considered a fundamental
topic to be investigated [3]. Thus, it is worth considering the case of the shrimp H.
inermis, that is a grazer of benthic diatoms of the genus Cocconeis, to understand if,
in the absence of fossil records, the ecological and physiological patterns discovered up to date aid in separating the rate and time components of evolutionary
changes in either or both organisms. Evidently a selective pressure is mutually
exerted, but in this case, a skewed pattern of advantages is observed in the two
species, because the shrimp evolved the ability to use teratogenic compounds,
normally produced as anti-grazer agents, to improve its sexual maturation and the
fitness of natural populations. As in the case of other long-term biological interactions (e.g., symbiosis vs. commensalism, parasitism, etc.) we propose here to widen
the concept distinguishing between the “evolution of cooperation” and the “evolution of competition”, thus introducing the theoretical notion of “competitive coevolution” [4], according to the evolutionary game theory [5], as an agonist
alternative to the “cooperation co-evolution”. In both cases, the establishment of
either “cooperator–cooperator” or “defector–defector” links facilitate the formation
of a hierarchical interaction structure leading to a favorable environment for two or
more species [6].
136
V. Zupo
leaves of the plant. Co-evolutionary relationships are often viewed in light of
mutual cooperation between two species. However, the peculiar case of H. inermis
indicates the need to widen the concept, integrating various adaptations that may
lead to different degrees of advantages for two co-evolving organisms. Shrimp’s
populations are stabilized in P. oceanica meadows thanks to this very specific
relationship, and they can survive a high predation pressure by fish and other
invertebrates because the secondary reproductive burst in fall produces sufficient
specimens for the next spring.
Keywords
Chemical ecology · Adaptation · Co-existence · Feeding · Food webs · Apoptosis
1
Introduction
Co-evolutionary processes often lead to mutualistic associations where two partners gain reciprocal advantages from the interactions in the same environment [1],
by following a process of joint adaptations between species [2]. The concept was
initially developed to explain the evolutionary forces driving the selection of two
species having close physiologic or ecologic relationships, to obtain mutual advantages. In contrast, the example of the shrimp Hippolyte inermis and the diatoms of
the genus Cocconeis indicates the evolution of a struggle for survival, leading to
organic diversification of both species, aimed at surviving in a complex but
relatively stable environment as the one represented by Posidonia oceanica
meadows. Since the infancy of coevolution studies, “the examination of patterns
of interaction between two major groups of organisms with a close and evident
ecological relationship, such as plants and herbivores” is considered a fundamental
topic to be investigated [3]. Thus, it is worth considering the case of the shrimp H.
inermis, that is a grazer of benthic diatoms of the genus Cocconeis, to understand if,
in the absence of fossil records, the ecological and physiological patterns discovered up to date aid in separating the rate and time components of evolutionary
changes in either or both organisms. Evidently a selective pressure is mutually
exerted, but in this case, a skewed pattern of advantages is observed in the two
species, because the shrimp evolved the ability to use teratogenic compounds,
normally produced as anti-grazer agents, to improve its sexual maturation and the
fitness of natural populations. As in the case of other long-term biological interactions (e.g., symbiosis vs. commensalism, parasitism, etc.) we propose here to widen
the concept distinguishing between the “evolution of cooperation” and the “evolution of competition”, thus introducing the theoretical notion of “competitive coevolution” [4], according to the evolutionary game theory [5], as an agonist
alternative to the “cooperation co-evolution”. In both cases, the establishment of
either “cooperator–cooperator” or “defector–defector” links facilitate the formation
of a hierarchical interaction structure leading to a favorable environment for two or
more species [6].
136
V. Zupo