14.1.3 Eco-evolutionary Experience and Biological Invasions
Other than specialisation, the phylogenetic composition of recipient communities
can impact on the rate and nature of interaction reassembly, alien species establishment success, and ultimately, invasion. That is, when organisms are introduced into
environments with phylogenetically closely-related congeners, the accumulation of
interactions (especially more specialised associations) is expected to occur more
rapidly compared to environments lacking closely-related taxa (Darwin 1859;
Daehler 2001). Related to this, the successful ecological integration of aliens into
novel community contexts will also rely on the eco-evolutionary experience of both
the introduced species and the recipient community. That is, historical evolution that
has shaped a species’ adaptations to biotic interactions (ecology) in its native range
will be the basis for ease of integration into novel ecological contexts, such as those
underlying species invasions (Saul et al. 2013). The same applies to native species’
responses and eco-evolutionary experience with the newly arriving species. Therefore, attributes of eco-evolutionary experience on either side, alien versus native, can
be interpreted in terms of the alien species’ invasiveness and the native community’s
invasibility, respectively (Saul et al. 2013).
Integration of alien species into novel community contexts is then itself an
ongoing process that will change over time and likely operate over both short and
long evolutionary timescales, and will be influenced by residence time, i.e. time
since introduction (e.g. Heleno et al. 2012). It is therefore expected that different
insights might emerge when assessing the role of biotic interactions in allowing alien
species to transition along different stages of the introduction-naturalisation-invasion
continuum. While ecological integration is key to becoming invasive, interactions
that are lost following species introductions are obviously important, such as release
from specialist enemies. However, these losses may only be temporary. For widely
established invasive plants, for example, interactions with resident and native herbivores and pathogens are expected to accumulate over time (e.g. Crous et al. 2017;
Stricker et al. 2016), and the evolutionary component of such interactions has now
been demonstrated in many cases (e.g. Strauss et al. 2006). The incidence and extent
of such ‘catch-ups’ are expected to increase with residence time, as host abundance,
and thus a possible unexploited resource and its discovery, increases (Carroll et al.
2005).
In this chapter, we review evidence for the role biotic interactions play in
biological invasions in South Africa. Focusing on parasitism and mutualism, we
aim to summarise evidence from South Africa in support of various ecological and
evolutionary hypotheses put forward to explain species invasiveness and that invoke
biotic interactions. We do not treat commensalism in depth here, as this interaction
type is generally not clearly linked to any of the major ecological and evolutionary
hypotheses related to invasibility/invasiveness or hardly studied, and neither do we
focus on invasions in urban ecosystems (see Box 14.1 for a discussion of what has
14 Biotic Interactions as Mediators of Biological Invasions
395
Other than specialisation, the phylogenetic composition of recipient communities
can impact on the rate and nature of interaction reassembly, alien species establishment success, and ultimately, invasion. That is, when organisms are introduced into
environments with phylogenetically closely-related congeners, the accumulation of
interactions (especially more specialised associations) is expected to occur more
rapidly compared to environments lacking closely-related taxa (Darwin 1859;
Daehler 2001). Related to this, the successful ecological integration of aliens into
novel community contexts will also rely on the eco-evolutionary experience of both
the introduced species and the recipient community. That is, historical evolution that
has shaped a species’ adaptations to biotic interactions (ecology) in its native range
will be the basis for ease of integration into novel ecological contexts, such as those
underlying species invasions (Saul et al. 2013). The same applies to native species’
responses and eco-evolutionary experience with the newly arriving species. Therefore, attributes of eco-evolutionary experience on either side, alien versus native, can
be interpreted in terms of the alien species’ invasiveness and the native community’s
invasibility, respectively (Saul et al. 2013).
Integration of alien species into novel community contexts is then itself an
ongoing process that will change over time and likely operate over both short and
long evolutionary timescales, and will be influenced by residence time, i.e. time
since introduction (e.g. Heleno et al. 2012). It is therefore expected that different
insights might emerge when assessing the role of biotic interactions in allowing alien
species to transition along different stages of the introduction-naturalisation-invasion
continuum. While ecological integration is key to becoming invasive, interactions
that are lost following species introductions are obviously important, such as release
from specialist enemies. However, these losses may only be temporary. For widely
established invasive plants, for example, interactions with resident and native herbivores and pathogens are expected to accumulate over time (e.g. Crous et al. 2017;
Stricker et al. 2016), and the evolutionary component of such interactions has now
been demonstrated in many cases (e.g. Strauss et al. 2006). The incidence and extent
of such ‘catch-ups’ are expected to increase with residence time, as host abundance,
and thus a possible unexploited resource and its discovery, increases (Carroll et al.
2005).
In this chapter, we review evidence for the role biotic interactions play in
biological invasions in South Africa. Focusing on parasitism and mutualism, we
aim to summarise evidence from South Africa in support of various ecological and
evolutionary hypotheses put forward to explain species invasiveness and that invoke
biotic interactions. We do not treat commensalism in depth here, as this interaction
type is generally not clearly linked to any of the major ecological and evolutionary
hypotheses related to invasibility/invasiveness or hardly studied, and neither do we
focus on invasions in urban ecosystems (see Box 14.1 for a discussion of what has
14 Biotic Interactions as Mediators of Biological Invasions
395