chromatophores of Paulinella represent an attempt to achieve an evolutionary
benefit which allows competitive success against the biological groups mentioned
below, in Sect. 5. Microalgae such as Paulinella dynamically interact with bacteria
in the phycosphere, which is a zone surrounding the phytoplankton cell (Lee and
Jeon 2018), and those interactions may have evolutionary consequences for all of the
participants.
26.5 Other Ways of Benefitting from Chloroplast’s
Photosynthetic Activity
There are many ways in which species have cheated, or at least tried to level the
competition, by adopting photosynthetic cyanobacteria and algae without those
adopted photosynthesizers becoming organelles. Or, the photosynthesizing symbionts have at least NOT YET become organelles.
26.5.1 Lichens Are a Mutualistic Association with Fungi
in Which the Photosynthetic Symbiont Is Not
Intracellular
Lichens are one of these examples, and Fig. 26.15 presents what is called a Wolf
lichen. Lichens are typically bipartite composite organisms consisting of a
photobiont and a mycobiont. The photobiont may be either a cyanobacteria or a
green algae. There also are tripartite lichen symbioses which may contain both
cyanobacteria and green algae in addition to the fungus. Many fungal genera contain
members that form lichens. The mycobiont of most lichens is an ascomycete,
although a few lichens are formed by basidiomycetes. The photobiont does not
reside as an intracellular symbiont. Lichens contain their photobiont cells as a layer
enclosed by hyphae of the partnering mycobiont. The cyanobacteria and green algae
are photosynthetically active and contribute carbohydrates to this symbiosis. The
cyanobacteria additionally are capable of contributing fixed nitrogen. The fungal
hyphae serve by providing a protective shelter for their photosynthetic partner.
Lichens generally are found in terrestrial environments although there are a few
aquatic lichens. In terrestrial lichen symbioses, the fungus may serve by providing a
surface area that can capture and retain rainwater thus supplying the photobiont with
necessary moisture. The original lichen symbiosis might have been cheating, and all
of the other lichen symbioses could represent efforts to level the competition. I used
this image of a Wolf lichen when I created the artwork “Volvox reimagined” that
appears on the cover of this book series.
Du et al. (2019) have demonstrated that cocultivation of mutualistic algae and
fungi could result in eventual internalization of the photosynthetic algal cells. The
26 The Game of Evolution Is Won by Competitive Cheating
561
benefit which allows competitive success against the biological groups mentioned
below, in Sect. 5. Microalgae such as Paulinella dynamically interact with bacteria
in the phycosphere, which is a zone surrounding the phytoplankton cell (Lee and
Jeon 2018), and those interactions may have evolutionary consequences for all of the
participants.
26.5 Other Ways of Benefitting from Chloroplast’s
Photosynthetic Activity
There are many ways in which species have cheated, or at least tried to level the
competition, by adopting photosynthetic cyanobacteria and algae without those
adopted photosynthesizers becoming organelles. Or, the photosynthesizing symbionts have at least NOT YET become organelles.
26.5.1 Lichens Are a Mutualistic Association with Fungi
in Which the Photosynthetic Symbiont Is Not
Intracellular
Lichens are one of these examples, and Fig. 26.15 presents what is called a Wolf
lichen. Lichens are typically bipartite composite organisms consisting of a
photobiont and a mycobiont. The photobiont may be either a cyanobacteria or a
green algae. There also are tripartite lichen symbioses which may contain both
cyanobacteria and green algae in addition to the fungus. Many fungal genera contain
members that form lichens. The mycobiont of most lichens is an ascomycete,
although a few lichens are formed by basidiomycetes. The photobiont does not
reside as an intracellular symbiont. Lichens contain their photobiont cells as a layer
enclosed by hyphae of the partnering mycobiont. The cyanobacteria and green algae
are photosynthetically active and contribute carbohydrates to this symbiosis. The
cyanobacteria additionally are capable of contributing fixed nitrogen. The fungal
hyphae serve by providing a protective shelter for their photosynthetic partner.
Lichens generally are found in terrestrial environments although there are a few
aquatic lichens. In terrestrial lichen symbioses, the fungus may serve by providing a
surface area that can capture and retain rainwater thus supplying the photobiont with
necessary moisture. The original lichen symbiosis might have been cheating, and all
of the other lichen symbioses could represent efforts to level the competition. I used
this image of a Wolf lichen when I created the artwork “Volvox reimagined” that
appears on the cover of this book series.
Du et al. (2019) have demonstrated that cocultivation of mutualistic algae and
fungi could result in eventual internalization of the photosynthetic algal cells. The
26 The Game of Evolution Is Won by Competitive Cheating
561