Friends or Foes (part 2)

Welcome back to my blog! Without further ado, let’s delve into the positive impacts!

Invasive species are good 

Non-native species can contribute to biodiversity conservation by acting as replacements for extinct species (Schlaepfer et al, 2011). However this is controversial as invasive species are widely known to cause loss of biodiversity like I’ve discussed in my previous post. In addition, they provide ecosystem services and are predicted to evolve into endemic taxa overtime (Schlaepfer et al, 2011).  For example, the Aldabra tortoises (Aldabrachelys gigantea), a close relative of the extinct giant tortoise, was brought over to the island of Ile aux Aigrettes to recover the island’s threatened ebony forest (Wolfe, 2015). Aldabra tortoises supported the dispersal of native plants’ seeds islandwide through consumption and excretion (Wolfe, 2015). Researchers reported that the ebony forest is steadily restoring (Wolfe, 2015). This highlights the importance of non-native species in the restoration of ecological balance.

photo of a Aldabra tortoise © TheOtherKev

But then again, nothing is black or white. We shouldn’t generalise that invasive species are either all good or all bad. We should always look at the context, which species and environment are we observing! For instance, zebra mussels can be both good and bad depending on the circumstances. In Lake Michigan, zebra mussels are deemed harmful as they poisoned thousand of birds to death while in Lake Ontario, zebra mussels have improved water turbidity which benefitted the marine ecosystem (Wolfe, 2015). 

There is a prevailing negative bias towards invasive species: between 1999 and 2014, 651 journal articles published presented invasive species in a negative context (Boltovskoy et al, 2018). I truly hope to see more coverage on the positives as sustaining an inherent bias would be harmful. Especially since “invasive species” and “non-native species” are used interchangeably.

The widespread objection and fear of the idea of non-native species would lead to missed opportunities to witness the beauty of evolution and restoration of ecosystems. Check out how the introduction of Gray wolves has radically changed the whole landscape of Yellowstone National Parks!

Besides, hasn’t wildlife been moving around the globe even before globalisation? The only tangible difference is the rate of spread due to human interventions. 

Yes, a portion of non-native species will be harmful but that doesn’t mean we should assume all non-natives are harmful until proven innocent. Recognising our bias is the first step to think rationally and objectively.
So, do they deserve such a harsh reputation?

 

References

Schlaepfer, Martin & Sax, Dov & Olden, Julian. (2011). The Potential Conservation Value of Non-Native Species. Conservation biology: the journal of the Society for Conservation Biology. 25. 428-37. 10.1111/j.1523-1739.2010.01646.x. 

Wolfe, 2015 retrieved from https://listverse.com/2015/05/04/10-invasive-species-that-helped-the-ecosystems-they-inhabit/

Boltovskoy, D., Sylvester, F., & Paolucci, E. M. (2018). Invasive species denialism: Sorting out facts, beliefs, and definitions. Ecology and Evolution8(22), 11190–11198. https://doi.org/10.1002/ece3.4588

8 comments

  1. Stacia Loong · September 21, 2020 at 11:54 pm ·

    Hi Li Xuan,

    Glad that you’re addressing the inherent bias people tend to have towards terms used. I always thought, however, that a species is first non-native and only becomes an invasive species when it is detrimental to its current ecosystem. Hence, the terms shouldn’t be used interchangably and invasive species are when they are harmful. Could you please clarify this please? Thanks!

    • glixuan · September 25, 2020 at 1:48 am ·

      Hi Stacia,
      I would like to point out that invasive species can be native too! (I mentioned it in my previous post, you can look at my reply to Li Zhe’s comment for more info) And yes I agree that those 2 terms shouldn’t be used interchangeably because indeed not all non-native species threatens the natural environment and native species. But I’d to clarify that its something I observed when I looked for articles/journals on invasive species, there’s a tendency to describe invasive species as exotic, non-indigenous and alien, giving readers the impression that they are non-native species.

      • Joanna Coleman · October 1, 2020 at 10:04 am ·

        Hi Lixuan,
        I don’t understand something in your reply. Indigenous means native. So how does it give the opposite impression ?
        Thanks,
        jc

        • glixuan · October 2, 2020 at 3:15 am ·

          Hi prof!
          Oh no I meant non-indigenous… I just edited it!

  2. Li Zhe · September 23, 2020 at 10:09 am ·

    Yes, I completely agree that context matters. Yet would you say that non-native species can be equated to invasive species as with the Aldabra Tortoise? Personally, I would think that we should be careful with using non-native and invasive species interchangeably. I think invasive species do in fact deserve their harsh reputation. Instead of fitting alien species into boxes like “This species is invasive, this one is not.”, instead I think we should be fitting the label onto the species taking into consideration the context, as you mentioned. What do you think?
    -Li Zhe

    • glixuan · September 25, 2020 at 3:02 am ·

      Hi Li Zhe!
      I totally agree with you, we should always look at the context especially at times invasive species do bring about positive effects depending on the context which tend to be overlooked! I used Aldabra Tortoise as an example, which is simply a non-native species, to show that non-native species can be harmless and even beneficial as seen with Aldabra Tortoise. Because there is a common misconception that “invasive species” is the same as “non-native species”. This misconception is prevalent in media and has made the idea of introduced species very controversial and often dismissed.

  3. ENV3102 · September 24, 2020 at 11:11 am ·

    Hi Lixuan,

    I would appreciate it if you could please acknowledge and address these errors of fact.

    Schlaepfer et al did not say that non-native species evolve into endemic taxa over time. They said that they SPECULATE that this MAY occur.

    Next, you cite the website listverse as the source of info about the tortoise in the Seychelles. But the very first sentence of the article suggests that the author believes the terms non-native and invasive to be synonymous. This should lead you to question the credibility of the source overall and reconsider citing it.

    Next, the example of grey wolves in Yellowstone is irrelevant to this discussion. These are animals that once flourished in this ecosystem but that were eradicated due to persecution. The outcome was a destructive increase in populations of their prey. In other words, they are native predators whose RE-INTRODUCTION was deemed necessary to save the ecosystem.

    Finally, this statement…
    “Yes, a portion of non-native species will be harmful but that doesn’t mean we should assume all non-natives are harmful until proven innocent.”
    It suggests confusion – i.e., using the terms non-native and invasive interchangeably. No credible conservation biologist assumes all non-natives are harmful. There is, however, a legitimate stance that INVASIVE species are deemed invasive specifically because they are somehow detrimental to native species, ecosystems or human interests.

    Why not write a follow-up post examining your own misconceptions and biases about your subject area and reflect deeply on the process of scholarly inquiry and your journey toward thinking more critically ?

    Thanks,

    jc

    • glixuan · September 25, 2020 at 4:23 am ·

      Hey Dr Coleman,
      Thank you for the feedback and highlighting these issues for me!
      That was poor research on my part, I simply assumed the wolves introduced were non-natives because it was mentioned that “From 1995 to 1997, 41 wild wolves from Canada and northwest Montana were released in Yellowstone“, I should have done further research as little can be safely deduced from that line.
      I organised and wrote this post poorly. I’ve failed to mention that it is a common misconception that has led to the interchangeable usage of invasive species and non-native species, which is commonly identified in articles and journals like the website I’ve used to obtain info about the Aldabra tortoise. This has led to a prevailing image that all non-natives are bad as they’re automatically viewed as potential invaders, especially by the lay public. I’ll be more careful next time… Thank you for rectifying my mistakes
      Thank you for that suggestion, I’ll definitely consider doing it!
      PS; these 2 comments were disapproved? I didn’t notice until I went to reply to the recent comment you’ve made